A case-control study on pleural malignant mesothelioma (MM) was conducted in Casale Monferrato, where the largest Italian asbestos cement (AC) factory had been operating from 1907 to 1985. In a previous study we observed a five to seven-fold increase in the incidence of MM among people living in that city and never employed in the factory mentioned. The present study includes cases of MM with histological diagnosis over the period 1.1.1987-30.6.1993 among residents in the Local Health Unit (LHU) of Casale Monferrato. Population controls were randomly extracted from the list of the residents in the LHU, matched to cases on sex, date of birth, vital status and date of death. Cases and controls (or their closest relative) were interviewed with a standardised questionnaire focusing on asbestos exposure in the (life-long) residential and occupational histories and in leisure time activities as well as on occupational asbestos exposure of relatives and cohabitants, smoking and chest or occupational diseases. The interview was blind in respect to case or control status. For the analyses the addresses were coded on map grids with a 500 m. mesh size. Statistical analyses were conducted with conditional logistic regression in order to keep the matching between cases and controls. Eighty-eight cases and 244 controls were interviewed (95.6% of cases and 80.1% of controls): 26 and 11 respectively reported an activity in the AC industry. Seven cases and 7 controls were also exposed because of parental occupation. The main analyses are based on the conditional regression model including both occupational and residential exposure. The different modes of exposure are included on an ordinal scale: each subject is classified according to their highest level. Domestic exposure is included as an independent factor. Odds Ratios (OR) are estimated with reference to subjects without either occupational or residential exposure. The OR is 39.3 among subjects reporting occupational exposure, 11.9 among those never engaged in the AC industry but living within 1000 m. of the factory. A statistically significant risk is also observed for persons at some time living in the other areas of Casale Monferrato.