Newborns with one large testicle and one small testicle may be considered to have pathologic conditions such as cryptorchidism, syringomyelia or hernia. 1. Cryptorchidism: there are abnormalities of testicular descent in the newborn period, which stays in the inguinal canal, retroperitoneum or the entrance of scrotum instead of descending to the scrotum, which can make the testicles one big and one small, but the testicles may descend on their own within the age of one year, so it can be observed and handled. 2. Syringomyelia: If testicular and spermatic cord syringomyelia occurs, the syringomyelia is closed at the inner ring before birth, but not closed at the spermatic cord, which can be connected with the testicular sheath capsule, so that the fluid in the testicular and spermatic cord sheath capsule will be accumulated, so that the scrotum will be big on one side and small on the other side. 3. Hernia: When the newborn baby often cries and causes the intra-abdominal pressure to increase, because the abdominal muscle is weak, thus inducing hernia. When hiatal hernia occurs, the hernia sac can enter into the scrotum, so that one side of the scrotum is enlarged, while the other side is normal. If you find that your newborn’s testicles are different in size, it is recommended that you seek medical attention and follow the doctor’s instructions.