The testicles of a three-year-old boy are normal as long as they are in the scrotum; if they are found to be absent from the scrotum or there is only one, a condition such as cryptorchidism or anorchidism is considered. In normal males, the testicles fall into the scrotum after birth, and in a few cases, within three months of birth. So, at the age of three years the testicles should be in the scrotum. However, the position of the testicles in the scrotum is not fixed and will have some degree of mobility. For newborn babies or children who are growing and developing, if the testicle disappears from one side of the scrotum, or if the testicle or scrotum is painful and swollen, we need to be alert to cryptorchidism, testicular varicocele, testicular torsion and other diseases.