In our hospital, 62 retinal detachments (RDs) in 58 patients who had previously been subjected to prophylactic argon laser photocoagulation (ALP), were operated on between July 1980 and October 1985. The incidence of RDs after prophylactic ALP has increased in recent years, being 3.90% (10 out of 256 RDs) in 1982, and 12.09% (26 out of 215 RDs) in 1985. The time interval between ALP and the occurrence of RD was less than 1 year in 54.7% of the patients, and between 1 and more than 10 years in 45.3%. Fifty per cent of the RDs developed after prophylactic ALP of retinal breaks. Fifty per cent of the RDs occurred after prophylactic treatment of degenerative lesions of the peripheral retina; 77% of the RDs in this last group occurred in eyes that had been subjected to 360 degrees photocoagulation. From the data obtained from the present series, the value of the 360 degrees technique for prophylactic ALP would appear to be rather questionable in most cases. In the present series, most RDs occurring after prophylactic ALP did not appear to be less severe than RDs in eyes that had not been subjected to prophylactic treatment.