Epidemiology is frequently neglected in the study of uveitis. Little is known on the incidence and prevalence of this disease. This review presents data on the subject from the literature and from the uveitis clinic at Rotterdam.The distribution of uveitis varies in different parts of the world and these differences might be attributed to geographic, alimentary or genetic factors. The discovery of associations of certain types of uveitis and HLA antigen subclasses provided at least part of an explanation for racial and genetic factors. These associations are dealt with in more detail.