Diabetes is known to be a major contributor to blindness in industrialized countries but few data are available on the situation in Italy. As an introductory step to the implementation of permanent screening for diabetic retinopathy, a search was carried out on the causes of visual loss in the provincial territory surrounding Turin, the main city of North-West Italy. The case notes of all 4549 residents in the province who were certified blind between 1967 and 1991 were examined with regard to cause, age at onset, and year of onset of visual acuity < or = 1/20. Diabetic retinopathy was the second commonest cause of bilateral blindness (13.1% of cases), preceded by cataract (26.7%) and followed by myopia (11.1%), optic atrophy (8.9%), glaucoma (8.9%), retinitis pigmentosa (7.2%), and senile macular degeneration (4.1%). Diabetic retinopathy was the commonest eye disease among those who became blind between the ages of 50 and 70 and remained the leading cause of visual loss when the age groups 20 to 70 were pooled together. The incidence of diabetic retinopathy-related blindness did not show any trend to decrease over the 25 years investigated. It is concluded that, in spite of widespread availability of facilities for its assessment and treatment, diabetic retinopathy remains a leading cause of blindness in North-West Italy. This fully justifies the implementation of screening programmes and efficient referral chains for the early detection and prompt treatment of this complication of diabetes.