The three-stage bone scan has been known as useful nuclear imaging for diagnosis of osteomyelitis, but when osteomyelitis is superimposed on an area of healing fracture, postsurgical changes, neuropathic osteopathy and primary and secondary bone tumor, the specificity of three-stage bone scan falls markedly. Because these conditions increase bone turnover, the differentiation between osteomyelitis and these conditions is difficult with three stage imaging technique. Recently, however, In111-labeled WBC scan is reported as a useful technique for complicating osteomyelitis. Thus In111-labeled WBC scan and three-stage bone scans were studied for 16 cases of suspected in-fection of bone, joint and soft tissue. In this studies, the results are follows:l. In111-labeled WBC scan is a more specific to diagnosis of osteomyelitis and septic arthritis than three-stsge bone scan. 2. When osteomyelitis was suspected in open fracture or postoperative bone surgery, In111-labeled WBC scan was positive only in infected cases, but in non-infected cases, it was negative. 3. In111-labeled WBC scan is useful for follow up study after surgical treatment of osteomyelitis.