This project was initiated by a veterinarian, that at stallion performance tests for breeding during a number of years, noted breed differences in various types of testicular disorders. Therefore it was of interests to examine the proportion of testicular disorders within certain breeds. The aim with the project was in a first part to study cryptorchidism in common horse breeds in Sweden. Information about castrations of stallions performed during a 10 year period (2000-2009) was collected from computerized case records at five animal hospitals. The case records showed the numbers of castrations, normal cases and cases preformed on stallions with cryptorchidism, abdominal respectively inguinal.