Available data concerning maldescended testes in the period 1982-1985 were collected from the Danish National Register of Hospital In- and Outpatients: 4935 operations were carried out in 4475 patients. The median age at time for operation varied between 11 and 12 years. Cohort analysis and cross section studies suggested that the true incidence of maldescended testes was approximately 2%. Based on incidence studies in literature, the number of boys with severely retractile testes operated upon could be estimated as approximately 1%.