We report a case of the complete separation of the testis and epididymis in an undescended testis, which is a very rare phenomenon. It is a situation associated with an undescended testis and appears to be one of the cases of fusion abnormalities. In all reported cases, vas deferens andepididymis or the vas deferens alone were located more distally than the undescended testis. In our case, histological examination of the left vas-epididymis complex showed rete testis-like tubular tissue which has a risk for malignant transformation. Long-term observation is essential.