In the years 1981-85, 2438 malignant neoplasms of peritoneum occurred in Italy: the crude mortality rate was 0.86 X 10(-5) per year. The standardized mortality rates of Italian provinces ranged from 0.20 to 1.86 X 10(-5) per year. Some degree of misclassification can affect the ascertainment of peritoneal tumors as a death cause. In some of the Provinces with the highest mortality rates dockyards or asbestos-cement industries are located (e.g. Genova, La Spezia; Alessandria); in other Provinces the presence of industries involving an important use of asbestos could not be ruled out.