It is widely recommended that infant boys with undescended testes (UDT) should be referred for surgical opinion before the age of 18 months. To attempt to identify the reasons why the mean age at orchidopexy in our institution was as high as 5.5 years, a retrospective review of the screening history, examinations, and management of boys over the age of 3 years at the time of orchidopexy was undertaken by reference to community, general practitioner, and hospital records. In 36 children where hospital and community records giving information prior to referral were available, the UDT had previously been documented on at least one occasion as descended in 24 children or retractile in 10. In 1 child there was delayed referral, and in another, there was operative delay. It is concluded that there is either frequent failure of the Child Health Surveillance screening programme, or that late ascent of a testis previously sited in the scrotum is a common occurrence. We recommend further prospective studies to clarify this latter phenomenon.