BACKGROUND This study is an attempt to assess the effects of chemonucleolysis over an extended period of time (8 to 12 years follow-up). METHODS From 1981 to 1985, chemonucleolysis using Chymopapain was performed on 134 patients for the relief of radicular pain from herniated lumbar discs. The long term results were evaluated in 110 patients. This represented a total follow-up rate of 82 per cent. 24 patients were lost to follow-up. RESULTS Of the 110 patients who had been reviewed at 8 to 12 years follow-up: 76 patients did not need other treatment than the initial chemonucleolysis. The results were excellent or good in 69 patients (63 per cent) and fair in 7 patients (6 per cent). 34 required surgery (31 per cent). This rate does not reflect the real failure rate of chemonucleolysis: 7 patients underwent early surgery and corresponded with the beginning of our experience with chemonucleolysis. 7 patients needed surgical treatment after a successful initial result for two to nine years. The real failure rate concerned 19 patients (17 per cent). These patients did not have any pain relief following chemonucleolysis. Surgical treatment was undertaken on the average 18 months after chemonucleolysis. One patient had suffered from radicular pain 6 years following the first chemonucleolysis. In this case, iterative chemonucleolysis had been done on the same lumbar level. It was effective on the radicular pain but not on the back pain. Chemonucleolysis had been effective in 70 per cent of the patients. CONCLUSIONS Our study showed that the long term results following chemonucleolysis were effective and the mortality rate was low. (No severe complication in this study). This study is compared with the literature, studying the results of chemonucleolysis patients, or comparing patients treated by chymopapain or surgical discectomy. CONCLUSIONS We conclude that chemonucleolysis is an effective and safe method for treating sciatica by herniated lumbar discs.