A total of 468 cases of bone, soft tissue and visceral sarcomas (and certain other tumours) diagnosed during the years 1982-84 in North West England were entered in a study of histopathological peer review, incidence and survival. This paper describes the effects of peer review. Material was reviewed by a panel of five pathologists for 413 of the 450 cases originally registered as sarcomas with the Regional Cancer Registry. The diagnosis of sarcomas was confirmed in 76% cases and and there was agreement on sub-type for 53% cases. Measures of agreement were lowest for the two sub-types most commonly diagnosed i.e. malignant fibrous histiocytoma and leiomyosarcoma. Degree of agreement between individual pathologists and final panel diagnosis was also very variable but never less than 65%. It is concluded that second opinion is essential in cases of presumed sarcomas for studies of incidence and aetiology and to ensure that appropriate treatment is selected.