Of 208 chemonucleolysis procedures performed between April 1973 and June 1978, 189 (91%) were available for follow-up evaluation by comprehensive questionnaire after six to 11.2 years. Pain relief, activity level, and personal satisfaction are considered in patients otherwise eligible for discectomy. The procedures were done under general anesthesia with 18-gauge single needle technique using biplane image intensification and routine discography prior to Discase injection. Seventy-nine percent of patients were satisfied with their results, 85% males and 65% females. Sixty-two percent of workman's compensation patients and 57% of patients previously treated by laminectomy had a satisfactory result. Ninety-five percent of patients had disc space narrowing postoperatively. Complications were few and of no lasting concern. Of the failures, 12.7% had laminectomies within 18 months of injection while 9.5% had a satisfactory result for at least two years. Disc reexpansion was demonstrated after postinjection narrowing in 14% of 58 cases roentgenographically evaluated, including patients of the 2nd, 3rd, and 4th decade of life. Recurrence rate in the total series was 9.5%. Chemonucleolysis is the least traumatic invasive procedure capable of removing the nucleus pulposus and is most effective when used in the treatment of lumbar disc herniation with objective signs of nerve root compression. In this series, approximately 80% of patients were spared open surgery.