In this study the effect of a buckwheat herb and a Ruscus extract preparation, compared with troxerutin, are described with respect to ophthalmological and biochemical parameters in patients with non-proliferative diabetic retinopathy. During the study period of 3 months, 60 diabetic patients were divided into three equal groups: in group I troxerutin was given, in group I1 Ruscus extract and in group I11 buckwheat herb was administered. At the beginning and on the last day of the study, each patient was subjected to ophthalmological and clinical biochemistry. The amplitude of oscillating potentials was decreased in patients receiving troxerutin, but increased in group I1 and group 111. Regression of changes located in the fundus of the eye was demonstrated in 23.1%-27.8% of all treated patients, however deterioration in 5.6% of patients given troxerutin and in 3.3% of subjects treated with buckwheat herb was observed at the same time. No cases with progression of abnormalities in the fundus of the eye were found in group 11. Moreover, troxerutin seemed to be less effective, especially when oscillating potentials were concerned. The use of buckwheat herb for the prophylaxis and treatment of diabetic patients, suffering from retinopathy is recommended.