The Rugby Football Union (RFU) has admitted an Aviva Premiership player could go an entire season without being tested as it published its annual doping report for the 2016-17 season.
Figures for last season revealed there were no anti-doping violations in the professional game from a total of 623 tests. One player failed an illicit drugs hair test, a decrease from 2015-16 when two positive results were returned.
However, it has emerged that while England stars are typically required to return samples eight to 12 times each season across club and international duty, that figure drops to as low as zero for a Premiership player.
"Some would be tested three times a season, but some would go a season without being tested," the RFU's anti-doping and illicit drugs programme manager Stephen Watkins said.
"If a player did go a season without being tested, we'd flag it with UK Anti-Doping to make sure we pick those players up."
As part of the report, which is in its seventh year, clubs across the Aviva Premiership, Greene King IPA Championship and Tyrrells Premier 15s are required to attend compulsory anti-doping education seminars -- 47 of which were completed last season.
"We take our responsibility towards anti-doping very seriously and I'm delighted to see that the report yet again has returned a clean bill of health," Phil Winstanley, Rugby Director at Premiership Rugby, said.
"Our support for education and our support for UKAD's testing programme ensures that we can demonstrate a clean Premiership competition and that our players are committed to a drug free culture.
"The illicit drugs programme was introduced in 2010 following concern about societal trends. I strongly believe that we need to continue to support a player-centred approach with counselling support for any player who fails a test but that there should be no second chance.
"This report endorses this approach with a very low number of players having returned positive tests over the years and no player having reoffended."
One hundred and nineteen tests were carried out across the amateur game, with two anti-doping violations returned and a further case still to be confirmed.
Information from the Press Association was used in this report.