The prevalence of abnormalities of cardiovascular reflexes as a marker of autonomic neuropathy was studied in a group of juvenile diabetics with long-standing disease, aged 20-58 years (mean 36). No patient had clinical evidence of autonomic failure. The study was carried out employing the most simple techniques and routine equipment. Resting heart rate, beta-to-beat variation, Valsalva ratio, systolic blood pressure in supine position and immediately after standing were measured. The results were compared with those determined in an age and sex-matched population. Beat-to-beat variation test appeared to be the most sensitive technique in detecting an impaired autonomic function (12/54 = 22.2%). Resting tachycardia was found in 10 patients and postural hypotension in 6. Only 1 patient had an abnormal Valsalva ratio associated with postural hypotension and reduced beta-to-beat variation. In agreement with previous studies our data confirm that autonomic dysfunction is frequent in asymptomatic diabetics. The methods to detect these abnormalities are easy to perform. Therefore they may be routinely used as screening tests in the diabetic population.