A prevalence study of diabetic eye disease was conducted in Newcastle during 1977-1978. Ophthalmoscopic retinopathy was found in 49% of 1210 clinic diabetics, while vision-threatening retinopathy (VTR) (proliferative signs of maculopathy) occurred in 13%. Maculopathy was the commonest cause of visual loss, occurring frequently in subjects with non-insulin-dependent diabetes. This group has now been followed for up to seven years (including 70% at four years); incidence rates for the development of retinopathy and for progression to a vision-threatening stage can now be estimated. The study found that diabetics with no retinopathy developed this at a rate of 8% per year, while only 0.4% per year progressed to VTR. However, once any retinopathy was present, progression to VTR occurred in 6% per year (2% proliferative and 4% maculopathy); and if any retinal signs indicating the presence of capillary closure were noted the rate was 13% per year. These rates are for the group overall: however, certain parameters were found to influence the progression in individual patients. Included were the age at onset and the duration of diabetes, the presence of poor control (particularly in older diabetics on oral agents) or associated nephropathy. An analysis of these data and their implications for routine eye screening of diabetics is presented.