The CFL said in a statement Monday that Thigpen tested positive for the steroid dehydrochloromethyltestosterone in a random in-competition test last November.
Under the policy, a suspended player cannot participate in regular season or post-season games. It is up to the team to determine whether that player can participate in other team activities, such as practices and meetings.
Thigpen will be eligible to take part in pre-season games
"We are disappointed in Marcus and that he has tested positive for a banned substance,'' Roughriders head coach and general manager Chris Jones said in a statement. "We have been in conversation with Marcus and the CFL for clarity and accept the leagues decision and corresponding two-game suspension. Our organization fully supports the CFL/CFLPA policy preventing the use of performance-enhancing drugs.''
Thigpen is in his second stint with the Riders after the CFL club signed him to its practice roster in September. While not making a large impact over the regular season, he rushed for 169 years and a touchdown on 15 carries in the Riders' 31-20 win at Ottawa in the East Division semifinal.