Incomplete descent of the testes is the most common genital anomaly in newborn boys. The prevalence varies with apparent geographical differences. The etiology of cryptorchidism is considered to be multifactorial (genetic, maternal, and environmental factors), and it occurs most often as an isolated disorder with no obvious cause. Cryptorchidism should not be left untreated, since there is an increased risk of developing testicular cancer and infertility/subfertility. However, the mode and timing of treatment, as well as the risks of subfertility and testicular cancer have long been controversial. There is increasing evidence that treatment should be performed early in life. Randomized volumetric and histological studies have shown that early treatment before the age of one year is beneficial for testicular development and future spermatogenesis compared to later treatment. It remains to be proven that this difference persists into adulthood. Due to the low efficacy rate and the possible adverse effects of hormonal treatment, surgery is preferred. The exact optimal time for orchidopexy is not known, but it should probably be before one year of age, at centers with expertise in pediatric anesthesiology and pediatric surgery/urology. The risk of testicular cancer is also reduced if orchidopexy is performed before puberty; however it remains to be proven if treatment in early infancy reduces the risk even further.