A condition similar to proliferative vitreoretinopathy (PVR) in man can be produced by injecting 25,000 homologous dermal fibroblasts into rabbit eyes following gas compression of the vitreous. Daunorubicin (15 nmol) was effective in preventing retinal detachment in this model when injected simultaneously with the fibroblasts or in two doses (10 nmol followed by 5 nmol 4 h later) on the 3rd day after fibroblast injection. A single dose of 15 nmol on the 3rd day was not effective in preventing retinal detachment. These results suggest that daunorubicin may be clinically useful in preventing PVR when given by injection both at the time of vitrectomy as well as later, when protein exudation and pigment clumps in the vitreous cavity herald the onset of PVR.