The club runs four senior sides and have a flourishing junior set up with many players going onto to play 1st team rugby.

[1] In October 1897 a former pupil of Dulwich College wrote to the school magazine (The Alleynian) bemoaning the fact that despite the school having an old boy representative "in almost all the first-class football clubs"[1] the fact that it did not have an old schoolboy team, "such as Old Merchant Taylors, Old Leysians, Old Carthusians, Marlborough Nomads", meant that it was missing out on "the greater athletic reputation [it] would otherwise have obtained.

[2] A second Surrey Cup win in 1992 was followed by a three year slide, seeing the club drop three divisions to London 3 South West.

The 2002/03 season saw the start of a resurgence and stability under the captaincy of James Franklin and Tim Sandars, when Old Alleynians beat Shipston upon Stour 16 -10 in the final of the Powergen Junior Vase,[4] held at Twickenham, with future Nothampton and Sale Number 8, Mark Easter starting in the match.

After staving off relegation on the final day of the 2012/13 season with a 26-24 victory away at Portsmouth, OA's began to establish themselves as Level 7 side.

The 2022-23 season, under captains turned coaches James Knox and Charlie Thompson, saw OA's win their first league and national cup double.

In May 2023, Twickenham Stadium would once again play host to a successful national cup run, gained with victories over Grasshoppers RFC (44-42), Wimborne (29-17), Dagenham (44-27) and Chobham (29-17) culminating in a 34-7 victory over Harlow in the inaugural Papa Johns Community Cup.

In April 2024, Fiona McIntosh became the first Old Alleynian woman to earn an international cap when she was selected for Scotland against the country of her birth, England.

[1] A semi-nomadic existence then ensued as the club moved on a yearly basis from Elm Grive, Sydenham to Cavendish Road, Merton to Horn Park Farm, Lee.