Mesothelial cysts of the spermatic cord (MCSC) are a rare entity. A 2-year-old cryptorchid boy with an inguinal mass was found to have a MCSC which was confused with undescended testis. The testis was readily placed into the hemiscrotum after excision of the cyst. MCSC may present as undescended testis and may be an unusual cause of acquired cryptorchidism. It should be excised and the inguinal canal should be explored for the existence of an undescended testis.