In a cohort of 268 type I diabetic patients, aged 19.6 +/- 4.1 years (Mean +/- 1 SD), with a diabetes duration of 10.4 +/- 4.9 years, treated by the same team, using the same conventional treatment regime during the total observation period, the progression rate of early retinopathy within the first two decades of diabetes was deduced from observed transitions of the retinal status from one stage of retinopathy (as defined by fluorescein angiography) to a higher one (Malone et al., 1977) within one year. A total number of 83 such events were evaluated. After a gradual development of earliest changes within the fifth year of diabetes, the median annual rate of progression was found to be 12-13%, independent of the previous duration of diabetes and the actual retinal state.