Fibroblast injection into the vitreous body causes traction detachment in the rabbit's eye. Various working groups reported different results on the main causes of the development of experimental PVR. These contradictions encouraged us to investigate the main source of experimental PVR by irradiating the ocular tissues before fibroblast implantation thus suppressing cell proliferation originating from host tissue. Over a period of 3 weeks, 22 eyes received ten radiations in a total dosage of 3000 rad. After the last radiation, 250,000 fibroblasts were implanted into 22 eyes. In another 4 eyes, fibroblast implantation but no radiation was carried out. After 8 weeks, 59% of 22 eyes developed different stages of retinal detachment. Comparison with the group of unirradiated eyes, which developed retinal detachment in 85%, revealed no significant differences in the number of detachments.