THE 618 cases of "idiopathic detachment of the retina" reviewed are those of patients examined and treated at the retina service of the Massachusetts Eye and Ear Infirmary between 1947 and July, 1951. During this period, operation has been performed in some cases without the participation of the retina service, and these cases have not been included in the group. Additional cases omitted from the group are those in which operation was refused, the cases of subclinical detachments, and a small number of cases in which insufficient data were available. The group represents the private patients of many different attending physicians and patients from the Infirmary clinics. The operators have been the senior and junior attending physicians and the retina service physicians, as well as the resident staff. Examinations before, during, and after operation have been carried out by these men and the retina service. During the last two years