Incomplete descent of one or both testicles from the abdominal cavity, through the inguinal canal into the scrotum is the most common abnormality in new-born boys; 3-5% are affected. Although a majority of these retained testes will descend spontaneously during the first few months after birth, about one percent of all boys will require some sort of treatment in order to achieve best possible testicular function. Thousands of publications deal with different aspects on cryptorchidism - most of them try to improve the mode of treatment; why, when and how should treatment be delivered? In order to summarize the present state of the art, a consensus conference with experts from the Nordic countries was called in August 2006. The conclusions and the appropriate literature reviews can be found in the May issue of Acta Paediatrica 2007.