The long-term prognosis of 60 patients operated on for carpal tunnel syndrome has been assessed in a prospective study with a median follow-up period of 5.5 years (range 2-11 years). Analysis of motor, sensory, trophic, and electrodiagnostic findings and assessment of pain were performed pre- and post-operatively using a standardized grading system. The results were generally favourable with a variable degree of improvement in 86% of cases. Statistical evaluation using multiple Dunn-Rankin tests revealed pain to be the most prominent pre-operative finding. On post-operative re-examination, pain was found to be improved to a significantly greater extent than any other variable. Analysis of several potential prognostic factors showed that pain lasting for more than 5 years prior to surgery indicates a poor prognosis. Only patients with diabetes mellitus exhibited a trend toward less pain relief.