Prolific try-scoring wing Tom Varndell ruptured his biceps during training on Wednesday, while back-row forward Rory Pitman suffered ankle ligament damage in Monday night's A-League game against Bath.
Wasps said on their official website that Varndell faces "three to four months" of recovery following an operation this week.
The former Leicester player has scored 73 Premiership tries, lying third on the all-time list behind Sale Sharks pair Mark Cueto and Steve Hanley.
Pitman, meanwhile, will also require surgery and faces a similar lay-off in terms of time to Varndell.
Wasps say five other players - Hugo Southwell, Elliot Daly, James Bailey, James Haskell and Phil Swainston - are unlikely to play in September, but are making "good progress" from their respective injuries.