To determine the prevalence and extent of autonomic neuropathy amongst Africans with insulin-dependent diabetes mellitus (IDDM), we investigated 50 such patients at our clinic. Mean age (+/- 1 s.d.) was 26 +/- 6 years, male:female ratio was equal (25M:25F) and duration of diabetes was 4.0 +/- 3.0 years. A battery of six validated tests of autonomic function was performed, testing both sympathetic and parasympathetic systems. Overall 16 (32%) had evidence of autonomic damage, affecting parasympathetic only in 14, and both sympathetic and parasympathetic in two. Those with autonomic neuropathy had a significantly longer diabetes duration than those without (6.0 +/- 2.8 years versus 3.1 +/- 2.7 years, P < 0.005), but there was no difference in glycosylated haemoglobin (HbA1) between the two groups. Autonomic neuropathy was also not significantly associated with peripheral neuropathy or other diabetic complications. Autonomic neuropathy carries a poor prognosis in IDDM and this high prevalence in a group of patients with relatively short diabetes duration gives cause for concern.