Objective To investigate the clinical effect of medical grade calcium sulfate(Osteoset) as a bone graft substitute. Methods From December 2004 to May 2005, 9 cases of bone defect(limb group)were repaired with Osteoset pellets; bone defect was caused by benign tumor inlimbs, including 3 cases of fibroma xanthomas in humerus(1 case) and acetabulum (2 cases), 2 cases of bone cysts in humerus(1) and radius(1), 1 case of nonossifying fibroma, 1 case of ossifying fibroma and 2 cases of osteofibrous dysplasia in femurs. Five cases of lumbar posterolateral fusion (spine group) were treated with Osteoset pellets as autograft volume expander, including 2 cases of lumbar spinal stenosis, 2 cases of lumbar spondylolisthesis and 1 case of lumbar spondylolysis. Radiological method was used to evaluate the repair effect of Osteoset pellets. Results The mean follow-up time was 6.2 months (3to 9 months). Osteoset pellets began to be absorbed after 1 to 3 months of operation, and were totally absorbed and replaced by osseous tissue after 4 to 6months. No local recurrence was detected in limb group and the function of limbs was normal. At 6 months after operation, all patients in spine group got bony fusion. Conclusion Medical grade calcium sulfate (Osteoset) isan ideal bone graft substitute with excellent bone repair effect.