In a retrospective study 79 patients suffering from a tumour of the testis were analysed between March 1977 and March 1983. Of these, 31 patients were examined via CT. The radiologist's task was the staging of these cases. The results show the superiority of CT diagnosis, which led to only one false-negative report. For the evaluation of stage II ultrasonography is useful, too, even though small lymphomas might be overlooked. If CT is not available, sonography, which is less costly, might be a good substitute. With regard to cooperative therapy, staging together with the histology of the primary tumour and determination of tumour markers are of essential importance.