To identify which patients are likely to respond the medical management of carpal tunnel syndrome, 331 hands in 229 patients were evaluated. They were then treated with a wrist splint and anti-inflammatory medication. Follow-up averaged 15.4 months (minimum six months). Treatment was successful in 18.4%. Statistical evaluation identified five factors which were important in predicting response to treatment: age over 50 years, duration over ten months, constant paraesthesiae, stenosing flexor tenosynovitis, and a Phalen’s test positive in less than 30 seconds. When none of these factors was present, two-thirds of patients were cured by medical therapy. 59.6% of patients with one factor, 83.3% with two factors, and 93.2% with three factors failed. No patient with four or five factors present was cured by medical management.