Centre Joe Ansbro and prop Alasdair Dickinson have been ruled out for Scotland ahead of Saturday's Six Nations opener against England.
But back-row forward David Denton has resumed full training after picking up a hamstring problem during Edinburgh's Heineken Cup victory over London Irish.
Ansbro, who was missing from the London Irish side that game, has not shaken off his back problem.
And Sale Sharks' Dickinson is still carrying a shoulder injury.
The 28-year-old, capped 24 times, was unable to train fully with the squad at their St Andrews base last week because of the problem he picked up in his club's Amlin Challenge Cup match against Brive earlier this month.
Scotland lead physiotherapist Paul McGinley said: "Alasdair was unable to train with the squad today as he is still recovering from the shoulder injury.
"We are returning him to continue his recovery with his club and we will reassess his situation after the England game."
The 26-year-old Ansbro - who has won nine caps for Scotland, scoring two tries - is back with London Irish but could also return to the national squad next week after being re-assessed by the Scots' medical staff.
"Joe came into our camp in St Andrews last week affected by a back injury which will need a longer period of rehabilitation," said McGinley.
"This will be undertaken at his club and he will be reassessed following the England game."
Denton won his first Scottish cap when he came on as a second-half replacement in the August Test against Ireland in 2011.