Abstract. To assess the prevalence of autonomic neuropathy (AN) in non-insulin dependent diabetes mellitus (NIDDM) and its relationships with other diabetic complications, duration of diabetes, and obesity, we evaluated 51 NIDDM patients (age 41–59 years, mean 49 years, duration of diabetes 0–15 years, mean 6.9 years). AN tests included a deep breathing test (E/I ratio) and an orthostatic tilt table test (acceleration and brake indices). AN was prevalent: almost half of the patients showed signs of AN (25 of 51, 49%) and the most frequent disturbance was an impaired E/I ratio (18 of 25; 72%). There were no obvious correlations between AN indices and the duration of diabetes, symptoms of AN, peripheral neuropathy or retinopathy. However, an influence of obesity on AN was suggested. Patients with AN showed a significantly higher BMI than patients without AN (31.0±0.9 vs. 27.5±0.8; P<0.01).