Testicular tumours are bilateral in 5.2% of cases although the incidence of bilaterality is affected by the mode of treatment of the primary tumour. A biopsy of the contralateral testis of testicular tumour patients will reveal carcinoma in situ in 5.5% of cases. In Denmark, most testicular tumour patients have a contralateral biopsy at the time of the primary orchidectomy, but in many countries general urologists and surgeons are not always aware of the advantages of simultaneous contralateral biopsy. Some specialist centres perform a contralateral biopsy as a secondary procedure once the patient has been referred. It has not been the policy in USA to take a contralateral biopsy at the initial orchidectomy, nor to offer a biopsy to patients after referral to a specialist centre. As a result of the discussions at this conference, urologists in USA will now be encouraged to take a contralateral biopsy at the time of initial surgery. If this is not performed, patients should be offered a biopsy after a full discussion of the advantages and possible side effects of the procedure so that informed consent can be given.