By means of a review of histological diagnosis in the Pathology Department of the University of Florence, suspected cases of malignant mesothelioma, diagnosed in the period 1979-1984, were identified. Study of histological specimens permitted the selection of 13 cases of malignant mesothelioma resident in the Province of Florence. To these cases, referents were matched for age, sex, and year of hospital admission, with residence weighted for the general population of the Province. Both cases and referents (or their next of kin) completed an occupational questionnaire detailing possible occupational exposures. Out of the 13 cases of mesothelioma, 6 were textile workers and 5 of these were "rag-sorters". There were only 5 textile workers among the 52 controls. No asbestos cloth production plants have been in operation in the area from which the cases and referents are derived. Possible sources of exposure to asbestos in the textile industry of this area are discussed.