Noninvasive tests for carpal tunnel syndrome (CTS) are of limited diagnostic value. A self-administered hand symptom diagram has been developed for use in the diagnosis and epidemiologic study of CTS. Diagrams are rated classic CTS, probable, possible or unlikely. Diagram ratings were compared with nerve conduction diagnoses in 110 patients with upper extremity complaints. A hand diagram rating of classic or probable CTS had sensitivity of 0.64, specificity of 0.73 and positive predictive value of 0.58. The negative predictive value of an unlikely diagram was 0.91. We conclude that the diagram is a useful diagnostic tool and may be valuable for occupational and population screening.