In a retrospective study of the case reports of 136 boys who were operated on for an imperforate anus and who survived at least 18 months, cryptorchidism was the most common associated anomaly, involving 26 cases (19%). The higher the level of the anorectal malformations, the higher was the incidence of cryptorchidism. The incidence of renal and ureteric malformations and dysplasias showed a parallel tendency. The incidence of vertebral malformations and dysplasias in the T10-S5 area was low among patients with a covered anus or a perineal fistula. Cryptorchidism was found to be associated with urological and with T10-S5 vertebral malformations and dysplasias. Recognition of this association is probably new. The histopathological findings of testicular biopsy specimens and the location of the undescended testes in patients with an imperforate anus showed the same pattern as seen in undescended testes from patients with cryptorchidism only. These findings, together with the existing literature on the subject, indicate that further studies on the association of cryptorchidism, urological, and T10-S5 vertebral malformations and dysplasias may be important for a better understanding of cryptorchidism in general.