Using Doppler duplex scanning retinal flow velocity was evaluated in 100 patients with carotid plaques, in 40 with hypertension and in 200 normal subjects. The reproducibility of the test was good. Peak systolic velocity was 12.5 cm/s in normals and significantly lower in patients with carotid plaques (9.8 +/- 6) and in patients with hypertension (8.3 +/- 6). The end diastolic velocity was also lower in both groups of patients. The ratio between the systolic and diastolic component was 2.3 in normals. It was increased in cerebrovascular disease (3.5) and in hypertension (5.5) as a consequence of the decrease in the diastolic component. In conclusion duplex retinal flow velocity evaluation is easy and reproducible and may be possibly used to study retinal flow in patients with cerebrovascular disease and in hypertension.