Hospital records were reviewed for 486 divers who have been diagnosed as decompression sickness(DCS) at Kangnam General Hospital between December 1986 and November 1988. Among 39 cases classified as serious DCS(type II), the patients had been fishery diving in 97.4% of the cases. The ages of the afflicted divers ranged from 22 to 47 years, with a mean of 31.5% years. The divers were experienced being less than one year in 21.6% and 70% of them learned diving skill by self-taught. In 86.5% of the cases the divers had made multiple divies ranged in depth from 31 to 50 meters. Thirty-one(83.7%) of the patients noted their first symptoms within 30 minutes of surfacing. The spinal cord was most often affected, and the most common symptoms were 'numbness' or 'tingling' in one or more extremities and discomfort or pain on the chest. Recompression treatment was delayed for 18 hours in average after the onset of dysbaric symptoms and this treatment is more likely to be effective the sooner that it commences after the onset of dysbaric symptoms.