In 1977-1990 a total of 2,554 patients with rhegmatogenic retinal detachment were operated by the cryosurgical method, using silicone episcleral implants. The total number of patients comprosed 36 (1.4%) where the authors detected during the preoperative examination retinal detachment, usually in an initial stage, on the other eye. In 30 patients the authors operated bilateral detachment of the retina simultaneously and in the remaining six during the same hospitalization. The poorer eye was characterized by 1. more extensive retinal detachment, 2. a higher grade of proliferative vitreoretiopathy (PVR). As to the preoperative findings, the authors consider the following points important: 1. Almost 70% of the patients did not report subjective complaints of the better eye. 2. With regard o the pathogenesis the patients were divided into three groups: lattice degenerations in 61.1%, idiopathic oral dialysis 11.1%, other factors 27.8% of the patients. 3. Symmetry of the retinal defect up to 90 in two-thirds of the patients. 4. Type of operation. On the poorer eye the authors performed segmental plombage in 12 eyes (33.3%), cerclage in 5 eyes (139%) and reinforced cerclage in 19 eyes (52.8%). For the better eye the authors indicated segmental plombage in 12 eyes (77.8%), cerclage in 4 eyes (11.1%) and reinforced cerclage in 4 eyes (11.1%). Subretinal fluid was punctured on the poorer eye in 19 eyes (52.7%) and on the better eye in 7 eyes (19.4%). After an average observation period of 40 months the retina became anatomically attached in 86.0% on the poorer eye, and in 100% on the better eye. Bilateral retinal detachment in our group can be considered a model situation of retinal detachment which developed roughly at the same time and under equal endogenous conditions of the given organism. It may be thus assumed that a different extent of detachment and grade or proliferative vitreoretinopathy before operation was determined above all by the period of retinal detachment.