To find out if ventricular dysfunction is related with diabetes duration or diabetic chronic complications, resting and exercise electrocardiograms, chest X-ray, echocardiograms and dynamic scintigraphy with left ventricular ejection fraction measurement (LVEF) were performed to three groups of diabetic subjects without known cardiopathy or hypertension: (I) twelve subjects with less than five-years diabetes, (II) eleven with five to ten years, (III) nineteen with diabetes lasting more than ten years. Results were compared with ten healthy volunteers. 90.4% of diabetics had at least one abnormality. LVEF was significantly lower in diabetics (P less than 0.001) than in control group. No important differences were found according to diabetes duration. Lower fractional shortening and lower cardiac output were found in group III than in control group (P less than 0.05). Impaired ventricular function in group III was related (P less than 0.05) with the evidence of diabetic late complications. Relationship between ventricular dysfunction and other microvascular abnormalities might suggest that microangiopathy participates in some extent to the pathogenesis of ventricular disorder.