Thalassaemic patients with diabetes mellitus are at risk of developing retinopathy. To evaluate the prevalence and the characteristics of diabetic retinopathy in thalassaemics we examined 46 patients with beta-thalassaemia major and insulin-dependent diabetes by fluorescein angiography. The study group was matched for sex, age and diabetes duration with a control group of 46 type 1 diabetic patients. Diabetic retinopathy was detected in 26% (12/46) of thalassaemics and in 50% (23/46) of the controls. In thalassaemics the diabetic retinopathy was significantly less severe than in controls (P < 0.0001). The influence of risk factors for diabetic retinopathy (duration of diabetes and metabolic control) was confirmed in the control group. In thalassaemic patients we found no significant correlation between these risk variables and the presence of diabetic retinopathy. Various factors may protect thalassaemics from diabetic retinopathy: heterogeneity of pancreatic functions; high incidence of hypogonadism; contemporary dysfunction of GH and/or glucagon secretion.