Since 1977 the diffuse malignant mesothelioma of the pleura and peritoneum caused by asbestos represents one of the most often compensated occupational cancers in Germany. Because of the probability of an asbestos-related etiology, it is considered as a "signal tumour", mainly indicating exposure to asbestos dust at the workplace. Two cases of histologically confirmed rare malignant mesothelioma of the tunica vaginalis testis are presented. Previous exposure to asbestos at the workplace is to be considered as a causal factor in both tumors. If cases of mesothelioma occur the criteria for indicating an occupational disease (No. 4105 of the German Law of Occupational Diseases, BKV) are fulfilled.