The authors recall that exploratory orchidotomy remains an essential operation for the diagnosis of testicular cancer and orchidectomy constitutes the primary therapeutic procedure. The operative technique is described together with its intangible principles, its difficulties and its variants. The tumour markers are best assayed on a sample of cord blood. The insertion of a testicular prosthesis, which is usually well supported, decreases the psychological effects of castration and does not cause any delay in possible adjuvant treatment.