Even with a history of controversy and troubling complications, chymopapain has endured the test of time to show 30 years of clinical success in the treatment of herniated nucleus pulposus. Strict attention to indications, contraindications, and technique ensures safety and efficacy of treatment. A trend to decreased dosage may result in less postinjection spasm. Between 1982-1991, 121 adverse events in 135,000 patients were reported to the Food and Drug Administration and investigated. Seven cases of fatal anaphylaxis, 24 infections, 32 bleeding problems, 32 neurologic events, and 15 miscellaneous occurrences were found. Overall mortality rate was 0.019%. All categories were of lesser incidence than complications with laminectomy. Long-term results show that improvement after chemonucleolysis is maintained, whereas the outcome after laminectomy is reported to deteriorate with time. Cost savings with chemonucleolysis over laminectomy are largely a matter of shorter hospitalization. A protocol for cervical chemonucleolysis is being developed in the United States after good results have been shown in Spain and France. Other enzymes continue under investigation, but chymopapain remains the standard to which they are compared.