Cornerback Carlos Rogers and linebacker Rocky McIntosh are not expected to participate fully in the May 2-4 mini-camp.
Both are continuing to recover from knee ligament surgery last year.
On Friday, they did some light running and worked on agility drills under the watch of team physical therapist Larry Hess and assistant strength and conditioning coach Bobby Crumpler.
Second-year tight end Tyler Ecker, rookie quarterback Colt Brennan and rookie safety Kareem Moore are also sidelined due to injury.
Ecker has a groin injury, while Brennan had hip surgery on April 7 and Moore underwent arthroscopic knee surgery last Tuesday.
Rogers is coming off a knee ligament injury suffered in Week 8 last season. He underwent surgery to repair the knee in November.
His availability for training camp and preseason is also uncertain.
Rogers has targeted the 2008 season opener for his return, though. He said in early March that he was "making progress" with his rehab.
McIntosh suffered a knee ligament injury in mid-December and underwent surgery in January.
McIntosh's rehab has a shorter time frame, team officials said. He could be ready to participate in individual drills during mini-camp, but he may sit out team work.
McIntosh could be fully healthy by training camp.
Ecker re-aggravated a groin injury during off-season work, team officials said.
Ecker, the Redskins' seventh-round draft pick last year, missed all of 2007 after suffering a groin injury during training camp.
Brennan will be at mini-camp this weekend taking instruction from head coach Jim Zorn and offensive assistant Chris Meidt. He is not expected to participate in any drills, though.
Brennan had hip surgery on April 7. He was told it was about an 8-10 week recovery and rehab. He could be available to participate in some OTA practices in June.
Moore reported to Redskins Park on Thursday walking on crutches. He had arthroscopic knee surgery earlier this week.
Moore's availability for Redskins OTA practices in May is doubtful. Like Brennan, he could be ready to participate in OTA practices in June.