A retrospective analysis of 50 consecutive patients treated with chemonucleolysis and 50 treated with microlumbar discectomy was carried out. Similar clinical criteria for the diagnosis of “virgin” herniated lumbar discs were used. All patients had low back or radicular pain unrelieved by a minimum of 4 weeks of conservative therapy. Physical findings included a positive straight leg raising sign, weakness of the appropriate muscle groups, and a sensory loss or evidence of depressed reflexes. All had myelograms or computed tomographic scans demonstrating an extradural defect. Compensation cases were eliminated. Results demonstrated a 90% marked improvement in the microdiscectomy category and a 58% marked improvement in the chemonucleolysis group. Four per cent of the microdiscectomy patients were unimproved, and 18% of the chemonucleolysis group required a subsequent surgical procedure. The average postoperative hospital stay was 3 days for both groups. Because of the necessity for reoperations in the chemonucleolysis group, chemonucleolysis seemed less cost-effective than microdiscectomy.