Four cases of blind ureteric bud are presented. This unusual abnormality is the result of abortive development of a normal bud or, more frequently, of an accessory bud brought into being by abnormal or premature division of the primary bud. - The disputed relationship between this abnormality and congenital ureteral and vescical diverticula is discussed. It is felt that the embryogenetic and anatomopathological evidence justifies the inclusion of some of the latter within the more extensive term "blind ureteric bud".