The results of orchiectomy conducted by the abdominal and scrotum routes were compared in guinea pigs. The operation time, surgical complication and incision healing were evaluated. About operation time, there was no distinct difference between two routes. In the abdominal route, the prognosis of this case was favorable. Also the healing of an incised wound was uneventful one week after the operation. While in the scrotum route, the tunica albuginea testis and the visceral vaginal tunic are thin, so that the risks of injuring the testis and/or scattering the contents of testis seem to be high. Inflammation of the scrotum was observed in 4 out of 5 guinea pigs, that were operated by scrotum route. From these results, the abdominal route method is highly recommended in the orchiectomy of guinea pigs.