A total of 101 cases of osteosarcoma was obtained from the pathology file of the Department of Pathology, College of Medicine, Seoul National University during a period of 16 years beginning from January 1968 to December 1983. These tumors consisted of 94 cases (93%) of conventional intramedullary osteosarcoma, 4 cases (4%) of parosteal osteosarcoma, 1 case (1%) of periosteal osteosarcoma, and 2 cases (2%) of osteosarcoma arising form osteochondroma. A total of 94 cases of conventional intramedullary osteosarcoma consisted of 60 cases (63.8%) of osteoblastic osteosarcoma, 19 cases (20.2%) of chondroblastic osteosarcoma, and 15 cases (16.0%) of fibroblastic osteosarcoma. Conventional intramedullary osteosarcoma was most prevalent in the 2nd and 3rd decades (79.8%), and more prevalent in males than in females with male to female ratio of 2.6:1. But, the male to female ratio was 1:3 in parosteal osteosarcoma. The predilection sites were the femur and tibia. Both sites were almost equall involved in conventional intramedullary osteosarcoma. The height of the patients with osteosarcoma was more than 50th percentile in 72.5% of the cases. The chief complaints were pain and/or palpable mass, and the duration of symptoms prior to admission commonly ranged from one to three months. The duration of symptoms in patients with parosteal osteosarcoma was longer, and was more than 9 months in all 4 cases. Five year survival rate of osteosarcoma was 12%, and 2 year survival rate was 32.1%. The group of patients who were treated with surgery and adjuvant chemotherapy showed a trend of longer survival than other groups. The patients with fibroblastic osteosarcoma also showed a trend of longer survival than the patients with osteoblastic or chondroblastic osteosarcoma.