[Objective]To discuss bone marrow derived mesenchymal stem cells(MSCs) culture in vitro and the curative effect of repairing cancellous bone defects in rabbits with the compound of allogenic MSCs and fibrin.[Method]MSCs were isolated and culture-expanted from rabbit bone marrow.Cancellous bone defects were created on bilateral femur condylar in 15 Japanese big ear rabbits,the left bone defects were treated with allogenic MSCs and fibrin,the right were treated with fibrin only.The bone defects were examined radiologically and histoloyically at the 2nd,5th,8th week after operation.[Result]The defects with only fibrin implantation couldn't heal spontaneously and no bone formation were found at any time-point.In the defects with compound of MSCs and fibrin implantation,there were a few bone formation within 2 weeks.By the 5th week plentiful callus were found,at the end of the 8th week,the defects healed.There was no immune respone except a few inflammatory cells infiltrate.[Conclusion]The compound grafts of allogenic MSCs and fibrin shows low immunogenicity within 8 weeks and is an effective method for repairing cancellous bone defects.