Seasonal variations of rhegmatogenous retinal detachment (RRD) have been reported in only several studies, mostly from Central and northern Europe. In this study, seasonal incidence of RRD was determined and compared with sunlight exposure per season in the Mediterranean region of south Europe. The study was based on a retrospective review of medical records on 280 eyes of 272 consecutive hospital patients in the district of Split, Croatia, who were treated for primary nontraumatic phakic RRD over a 12-year period (1988-1999). The number of eyes with RRD recorded per season was 79 in summer, 71 in winter, 67 in spring and 63 in autumn. The average number of sunshine hours in Split was 1001 in summer, 698 in spring, 576 in autumn and 457 in winter. No seasonal variations in the occurrence of RRD and no correlation with the mean duration of sunlight exposure per season were found.