Andrew Acton, a 22-year-old prop who was playing for top-flight Ayrshire club Marr RFC, has been suspended for three years and nine months after an out-of-competition positive test for stanozolol, a synthethic steroid, in August.
Acton was immediately suspended by Marr, who are currently bottom of the Premiership, when the provisional test became known on the eve of the current season and the player has since left the club.
The South African, who joined Marr in 2016, is the fourth player within Scottish rugby to have returned a positive result after over 2,000 tests in association with UKAD since the 2009/10 season.
The most high-profile case is that of former Scotland Under-20 player Sam Chalmers, the son of Grand Slam hero Craig, who was banned for two years in 2013, also for steroids use.
An SRU statement read: “Scottish Rugby is fully committed to the fight against doping to protect the integrity of the game.
“As a governing body, we have an extensive education programme for players, at all levels, on the consequences of taking banned substances, from both a health and sporting perspective.
“This season Scottish Rugby has upweighted its activity with UK Anti-Doping to generate more intelligence led tests in and out of competition, for professional and club players alike.
“We welcome Andrew Acton’s ban as it serves as a timely reminder to all players that they have a responsibility to adhere to the anti-doping code and the use of banned substances has no place in our game.”
Marr RFC president Kevin Quinn said: “We are very disappointed that a young player has compromised his rugby career by taking a banned substance.
“Marr fully supports the SRU’s work providing guidance to players aimed at keeping the sport clean.”