Ocular fluorophotometry (OFP) was performed on 38 normal subjects and 71 patients with essential hypertension who showed hypertensive retinal vascular change without hemorrhages and exudates. The average fluorescein concentration one hour after dye injection in the posterior vitreous and the anterior chamber of hypertensive patients was higher than that of normal controls. In patients who showed only minimal arteriosclerotic change or minimal arteriosclerotic plus minimal hypertensive change, at 60 minutes fluorescein values in the posterior vitreous and anterior chamber were at normotensive levels. Conversely, in patients who showed marked hypertensive change, the values were higher than in normal controls. Our results indicate that permeability may change in hypertensive patients even when no retinal hemorrhage and fluorescein leakage are observed by fluorescein fundus angiography, and OFP may contribute in quantification and grading of retinal vascular damage by hypertension.