The authors examined 103 eyes of 53 patients with insulin-dependent diabetes mellitus simultaneously by fluorescein angiography and vitreous fluorophotometry and correlated the stage of diabetic retinopathy with the posterior vitreous leakage (PVL) level, calculated from the preinjection-, bolus-, and measurement scans. There was a significant correlation between stage of retinopathy and PVL level, but there was a large variation of PVL readings within each group of retinopathy stages. All eyes were reexamined after a mean period of 11.84 months. In 15 of 16 eyes with progressive retinopathy the first PVL readings were within the distribution range of the respective retinopathy level. A progression of retinopathy was not accompanied by a significant change of the PVL. It was concluded that vitreous fluorophotometry alone is not sufficient for the grading of diabetic retinopathy and has only little prognostic value for the course of the disease.