There were 72 diabetic patients with clinical evidence of sensorimotor peripheral neuropathy investigated to determine the sensitivity of the sympathetic skin response test (SSR) for detection of sudomotor dysfunction and its correlation with other autonomic function tests, autonomic symptoms, and degree of peripheral neuropathy. Nerve conduction velocities (NCV) were abnormal in all patients, SSR was absent in 60 of 72 patients (83%), Valsalva test was abnormal in 32 of 67 patients (48%) who had the test, and 6 of 72 (9%) had orthostatic hypotension. Statistically significant correlation was found between the Valsalva test abnormality, the degree of peripheral neuropathy, and the SSR in our patients. All patients with orthostatic hypotension had an absent SSR and an abnormal Valsalva test. Most patients had one or more autonomic signs or symptoms. Orthostatic dizziness only correlated with SSR, however. These results suggest that sudomotor activity detected by sympathetic skin response is a valuable test for investigation of dysautonomia in diabetic peripheral neuropathy.