A 1-year-old boy was admitted to our department with undescended testis on the left side of the body. Upon surgical exploration, a diagnosis of polyorchidism was made. The accessory proximal testis was removed and the distal testis underwent orchidopexy. Pathological findings revealed duplication of the vas deferens and epididymis but without an accessory testis. We then performed further intra-abdominal exploration in order to identify intra-abdominal testis arising from complete urogenital nonunion. We concluded that this represents the first documented case exhibiting duplication of the vas deferens and epididymis.