Many patients with occupational diseases fail to obtain compensation because their disease is not recognized as occupational and reported to the authorities. The present study examined the reporting of pleural mesotheliomas and sinonasal adenocarcinomas--cancers with well-known associations with occupational exposures to asbestos and wood dust--in Denmark in 1983-1987. The estimated underreporting was around 50%. Examination of the medical records of patients who had not been reported in 1986-1987 revealed that in most cases the medical records did not contain sufficiently detailed information about occupational exposures. It was recommended that a formal screening interview be carried out whenever a diagnosis is made of a potential occupational cancer. Medical associations may play a major role by issuing guidelines addressing occupational diseases within the fields of their expertise.