• The vitreoretinal relationships of 312 eyes with diabetic retinopathy were analyzed statistically, based on the results of biomicroscopic observation and photography of the vitreous. Vitreous detachment usually occurs outside the temporal vascular arcades, and the macula subsequently becomes involved in the midstage of the proliferative process. The incidence of no vitreous detachment and complete vitreous detachment are significantly lower in proliferative retinopathy as compared with nonproliferative retinopathy. The incidence of partial vitreous detachment is significantly higher in proliferative than in nonproliferative retinopathy. The relatively high incidence of proliferation with no vitreous detachment indicates that vitreous detachment is not the sole triggering factor in the development of proliferative changes. However, partial vitreous detachment was shown, retrospectively, to stimulate a rapid exacerbation of the proliferative process as compared with eyes having no vitreous detachment or complete vitreous detachment.