The Scarlets set the benchmark for the 2004–2005 season in winning all three finals at U16, U18 and U20 levels. WRU High Performance Manager Mostyn Richards said of the championships, “These competitions will provide the breeding ground for our national age grade players at U16, U18, U19 and U21 levels. All national age grade teams have extremely tough programmes this season and this competition will certainly help us prepare our players for the challenges that lie ahead.”

The two younger Ospreys age groups secured their respective championship titles with relative ease, however, the eldest Ospreys age grade side had to endure a tough battle in the U20 tournament to achieve success. Starting a month later than the younger age grade championships, the opening round of the tournament saw the Dragons face the Blues at Abertillery Park with the Scarlets hosting the Ospreys at Stradey Park.

The reigning champions secured a first win of the season with a 27-18 win over their Osprey visitors. In a match featuring the two finalists of the previous season’s climax the Scarlets overcame the Ospreys in terrible weather. Darren Daniels, who had progressed into the senior Scarlets side this season, scored a first-half try that was converted Rhys Priestland but a try from Ospreys’ scrum half Martin Roberts kept the Ospreys within two points at half time. The Scarlets took control in the second half of the game with a try from Steve Martin and a penalty try also gained. Priestland’s ten points in the second half of the game extended the Scarlet scoreline and secured the win despite two tries from the Ospreys’ replacement scrum half Lee Gunnell.

The Dragons ground out a deserved 18-13 first round win over the Blues in torrid conditions; heavy rain and a gusty wind caused problems for both sides. The Blues attained the first score through a Jason Murphy penalty but opposite number Ashley Smith replied in kind in the fourteenth minute. Murphy secured his second a minute later to restore the Blues’ slender lead but the Dragons took the advantage soon after with the first try of the evening; Daniel Robinson touched down after a five metre scrum. The Blues were awarded a penalty try as the Dragons struggled with a depleted side due to two occasions of men in the sin-bin. Despite their numerical disadvantage the Dragons maintained pressure and after a length of the field movement, Marcus Johnstone crossed for a try that gained the first victory of the season.

Looking to build on their initial victory in the WRU Reebok Regional U20 Championship the Dragons took on the Ospreys at the Brewery Field in round two. However, it was the Ospreys who secured the victory as they took a 17-13 half time lead after James Pike, Mark Breeze and Andrew Gwyn had attained tries; Marcus Johnstone and scrum half Robert Lewis crossed for the Dragons. Ross Cridland scored the decisive try for the Ospreys in the second half as they claimed their first win of the season. The other fixture saw the Scarlets travel to Abercynon to meet the Blues. Bradley Davies snatched a brace of tries for the Blues with Tom Isaacs and Rhys Gill also adding one apiece. The Scarlets, though, overpowered their hosts, coming from behind in the dying minutes to clinch the win. Rhys Priestland scored a try and added five points with the boot whilst wing Alec Jenkins, Martin Thomas, Iwan Taffetsauffer and No.8 Lee Williams scored the tries, edging the final scoreline to 30-26.

The Scarlets entered round three with two wins from two games played, leaving them five points clear of the Ospreys. With a home advantage they maintained their winning streak in the championship over the Dragons at Narberth. In the seven-try comprehensive success wing Alec Jenkins was the star performer as he ran in four scores in the Scarlets’ romp. Outside half Rhys Priestland bagged a fifth, as well as notching a further twelve points with the boot; Josh Turnbull and Ashley Banfield completed the rout. The Dragons had remained close for a period in the first half as Richard Wilkes gained a try with Ashley Smith converting and adding a penalty. Yet the Scarlets stormed away for the emphatic 47-10 victory soon after and took a giant step towards the final of the Reebok Regional U20 Championship. Team manager John Davies commented on his side's superb performance, “To win with a bonus point, and to play in the manner that we did, was very pleasing. We just have to maintain our standards in the three remaining rounds.”

The Ospreys hosted the Blues at St Helen’s in the other round three match, with the Blues in need of a victory to retain any hope of making the final at the close of the season. Yet the Ospreys comfortably secured a 35-8 win to compound the Blues’ miserable start to the season with three losses from three matches played. The Ospreys gained five tries in the match, including a brace for James Pike, as the Blues only managed to attain a penalty from Gareth Williams-Davies and a second-half try from Jamie Roberts. Ospreys coach Gethin Watts said of his side’s victory, "It was tight early on but once we went over for our first try we took control. In the second half we played really well and in the end deserved to win it as we did."

The fourth round match between the Blues and Dragons was postponed but the pick of the fixtures, the Ospreys against the table-topping Scarlets, progressed at Swansea RFC. Before the game the Scarlets had amassed fifteen points from three games whilst the trailing Ospreys had ten from the same amount of matches played. This new year match would witness both teams vying for a berth in the championship final with the Scarlets looking to do the double over their hosts after beating them in the season opener.

However, it was the Ospreys who wrapped up the win and consequently closed the Scarlet advantage in the U20 table. Three tries, plus nineteen points from the boot of Jonathan Spratt, saw last season's losing finalists secure the 34-25 victory. The Ospreys had drawn out a 21-10 lead at half time due to tries from Alex Wilkins and Andrew Gwynne. Four tries for the Scarlets, including efforts from fullback Martin Thomas and hooker Ken Owens, together with Rhys Priestland adding a conversion and penalty were not enough to grind out a win as Nicky Roberts’s second-half try secured the Ospreys’ triumph.

The penultimate round in the U20 championship saw the Scarlets match against the Blues postponed but the Ospreys made another step toward the final with a 29-14 win over the Dragons at Abertillery Park. The Dragons gained an early lead through a twelfth minute try from Daniel Fox following a Marcus Johnstone break. The Ospreys struck back with a try from tight head prop Lloyd Jones and a penalty from Nicky Roberts but the Dragons took a 14-8 lead into the interval following a try from another prop, loose head Richard Cornock. The Dragons were unable to increase their tally by a single point in a second half that the Ospreys controlled. Leigh Bevan notched a second Osprey try after chipping the ball over the Dragons’ fullback whilst Roberts charged down a clearance kick for the Ospreys' third. Bevan completed the try count as he capitalised on a Dragons’ error to round off the full time score with his second score of the night.

The concluding round saw the Ospreys U20 book their place in the WRU Reebok Regional Championship with a last-gasp 31-26 victory over the Blues at the Arms Park. The Blues, still without a win in this season, led 26-10 with just ten minutes of play remaining following a brace of tries from James Connors, a solo score from Matthew Edwards and eleven points from Celyn Ashton’s boot. The Ospreys fought back as Anthony Rogers, Ross Cridland and Jonathan Spratt scored three converted tries in the dying minutes to snatch the crucial victory.

The game at Abertillery Park between the Dragons and the second placed Scarlets was postponed but took place in early April. With both sides hampered by the loss of strength due to the U19 World Championship in Dubai, where both sides were well represented, the teams ground out a draw. The Dragons led 24-21 going into the final minute but an eleventh-hour penalty from scrum half Liam Davies earned the visitors a draw.

With the Dragons and Blues unable to catch the Scarlets they progressed to the final with the Ospreys in a repeat of the U20 fixture of the previous year. The WRU Reebok Regional U20 Championship final was played as a curtain raiser to the Llanelli v Llandovery Principality Premiership game at Stradey Park on April 29th. The Ospreys hoped to reverse the previous season’s result, having lost only one of their six pool matches throughout the 2005–2006 season. However, the Scarlets had also had a successful season and would want to lift the silverware for the second successive championship.

Sam Kiley attained the first score for the Ospreys but his try went unconverted. The Scarlets replied through the boot of Rhys Priestland: he successfully chipped over two penalties to take the Scarlet advantage to 6-5 as the teams headed into the dressing rooms at half time. On the resumption the Scarlets extended their lead as centre Johann Taffetsauffer attained a converted try. The Ospreys soon struck back with a try from prop Neil White, which Nicky Roberts converted, to pull the scores to 13-12. The Scarlets soon improved on this one point advantage as Alec Jenkins crossed the Osprey line but Roberts added a penalty and attained a try to pull the Ospreys into the lead at 20-18. Osprey winger Leigh Bevan crossed for a late try to guarantee the Ospreys’ 25-18 victory and first Reebok Regional U20 Championship title.

Following in the footsteps of the Scarlets in the inaugural Reebok Regional Championships, the Ospreys had attained a clean sweep in the 2005–2006 season throughout the three age grade competitions. The season saw further success for age grade rugby as Wales U19, consisting of players from the four regional U20 sides, won a grand slam in the U19 Six Nations championship in March. Many of the U20 players also travelled to Dubai for the IRB U19 World Championship in which the Wales U19 team finished in sixth position.