Using bone marrow stem cell in treatment of bone and joint diseases has been interested to research. Objectives: evaluate the effect of using autologous bone marrow stem cell in treatment of nonunion of long bone, bone defect caused by distraction osteogenesis and aseptic osteonecrosis of the femoral head and determine the relationship between the number of stem cells which were grafted and the clinical outcome. Subjects: 133 patients were divided in to 3 groups: group I included 73 patients with nonunion of long bone, group II included 30 patient with short stature and in limb length discrepancy that were lengthened by llizarov's principle
group III include 30 patients with aseptic osteonecrosis of the femoral head. Methods: 20-30 milliliters of bone marrow stem cell mass were created from 250-350 milliliters of aspirated bone marrow fluid then injected in to sites of bone lesion. Results: in group I, 85.6 percent patient achieved bone union
in group II, the average bone healing time for 1 centimeter of length was 32.1 + or - 5.9 days
in group III, 80 percent patients had good outcome. There was relationship between the numbers of stem cell grafted and the clinical outcome in group I and II. Conclusions: bone marrow grafting was a safe and effective method in treatment of some bone diseases.