Osteochondroma is the most common of primary benign bone tumors. It is characterized by protruding mass from metaphysic of long bone with semitranslucent cartilaginous cap on its surface. This lesion, which has its own growth plate, usually stops growing at skeletal maturity. The multiple variant of osteochondroma, namely the osteochondromatosis, may show various deformities around the joints in its course. In addition, sarcomatous change is sometimes developed. One hundred and twenty one patients were diagnosed as osteochondroma or osteochondromatosis from Jan. 1981 to Dec. 1991, and followed-up for 3.4 years(6months-8years). There were 74 cases of solitary osteochondroma(male : female=1.47 : 1), and 47 cases of osteochondromatosis (male : female=1.61:1). The age at initial visit was averaged 19.5 years(2 years 8 months-58 years). In our experience, common sites were distal femur, proximal tibia, proximal humerus in solitary osteochondroma, proximal tibia, distal femur, distal tibia in osteochondromatosis. Mass with or without pain was the most common chief complaint. Familial histories were noted in 38% of osteochondromatosis. The deformity, which needed correction, were found in 10 among 119 cases ; corrective osteotomy in 7 cases, lengthening with Ilizarov apparatus in 3 cases. The complications such as limitation of motion, sensory disturbance, recurrence, persistent deformity after corrective surgery, epiphyseal plate injury, superficial infection, were noted in 28%. During the follow-up period, there were one case of malignant transformation, and recurrence was identified in 7 cases and three of them were reoperated. Interestingly, progressive deformity was noted in 3 cases postoperatively. And, if the tumor produces no symptom and no functional impairment, we recommend minimizing the indication of surgical intervention. In particular, special attention must be taken in growing children in order to avoid inadvertent complications such as progressive deformity.