Oscillatory potentials of the ERG proved to be a sensitive indicator even in mild disturbances of retinal circulation, such as the first stage of hypertensive retinopathy (WHO classification). Oscillatory indexes (OIs) and blood pressure levels of 24 hypertensive patients in stage 1 of the WHO classification, who underwent an antihypertensive therapy for the first time, were considered. The patients were retested after a mean period 8 months. a strict inverse correlation was found between OIs and blood pressure levels.