Using data obtained by questionnaire in a retrospective review of patients with low-back and sciatic pain (eighty-five treated by injection of chymopapain and seventy-one, by open discectomy), the results at one and ten years after treatment were analyzed. For this analysis we used six measures of pain relief, six measures of the patients' course during the ten-year period since primary treatment, and four measures of the patients' history of employment or work since initial treatment. Validity studies demonstrated that the pain-outcome measures reflected the patients' condition adequately and that all six measures were significantly related to each other (Pearson's r, p less than 0.003). The chymopapain and discectomy groups were not distinguishable on the basis of the pain-outcome measures. However, body mass was directly related to the presence of pain ten years after discectomy but not after injection of chymopapain. Analysis of the progress measures (indicators of the course of the patients' pain during the ten-year period) showed that the rates of reoperation in the two treatment groups did not differ significantly, but the discectomy patients tended to have had a higher rate of reoperation at both one and ten years after initial treatment. These measures did not show unequivocal superiority of one treatment compared with the other. Using the work measures (assessments of the patients' history of employment since initial treatment), it was found that in both treatment groups the patients who returned to work six to twelve weeks after treatment despite persistent symptoms had significantly more pain at ten years (p less than 0.04). Also, the patients who returned to work less than six weeks after treatment, while still symptomatic, showed a similar trend. On the other hand, among the patients who were still symptomatic at twelve weeks, it made no difference in the final results whether they returned to work at twelve weeks or thereafter. These findings support the notion that after either discectomy or chemonucleolysis, patients should return to work only after complete symptomatic recovery or a minimum convalescence of twelve weeks.