A review of 468 orchidopexies was undertaken to ascertain the importance of a complete hernial sac extending to or beyond the testis. A hernial sac was present in 84% (171/202) of testes in patients under 5 years of age, in contrast to 23% (61/266) in patients over 5 years. It seems reasonable to presume that the failure of the hernial sac to close is secondary to failure of normal descent, which in turn is due to antenatal factors and may be classified as "early maldescent". In the older age group maldescent is due to failure of the last stage of descent, which should occur in the 5- to 10-year prepubertal age period ("late maldescent", or the "ascending" testis). The cause of late maldescent is not due to a short processus, as this increases in length with age (approximately 0.5 cm/year), unless the persistence of the processus itself is the cause. A classification of early or late maldescent is suggested.