Authors examined 256 of civilian professional divers working at the shore of Southern, Eastern and Western sea in Korea for the studies of dysbaric osteonecrosis in divers. For each diver, a questionnaire was made of his/her past medical history, diving experience and frequency, diving depth and attacks of bends. Radiographs were taken of the shoulders, hips, kness and other joints especially when bone lesions in routine radiographs. Then the frequency of bone lesions, pattern of the osteonecrosis and the degree of progression of lesions were examined. 171 divers (66.8%) had bone lesions in one or more joints. The incidence of bone necrosis increased in proportion to the length of diving experience and increased significantly for men with over ten year's experience by 80.6%. Frequency for bone lesions of shoulders was the highest, 48.7%, then that of hips and knees are 37.2%, 14.1% respectively. Bone lesions were frequently multiple. In terms of radiological classification, segmental opacity (Al) had been shown the most common. The deeper the diving depth, the more the incidence of bond lesions. In proportion to the average length of a diving time, the incidence of bone lesions increased significantly. The incidence of bends attacks was high(88.7%) and the incidence of bone lesion increased proportionately to the incidence of bends attacks. But no significant relationship between the sites of the bends attacks and bone lesions was found. Those divers who experienced more emergency escapes owing to underwater accidents without decompression procedures had higher incidence of bone lesions and severe involement. The incidence of bone lesions was much higher for men of obese body character than of normal or slim body character. 92 divers (35.9%) 72 divers (28.1%) had avascular necrosis of the femoral head and 47 among them (66.2%) had bilateral lesions.