The main objectives of the National Mesothelioma Register (ReNaM), set up by the National Institute for Prevention and Occupational Safety (ISPESL), are: (a) the estimate of malignant mesothelioma incidence in Italy, (b) the definition of exposure to asbestos, (c) the identification of unknown contamination sources, still present on the territory. Cased diagnosed in 1997 in Piedmont, Liguria, Emilia-Romagna, Tuscany and Apulia are reported, regions with more than 17 million inhabitants (30% of national population). ReNaM has facilitated the identification of mesothelioma cases and the description of the previous asbestos exposure in a large geographical area of the country, even though in some regions the definition of exposure to asbestos is not complete. 429 cases are recorded, of which 326 (76%) have been defined as definite malignant mesothelioma. The standardized annual incidence rate just for pleural definite mesothelioma is 1.51 x 100,000 inhabitants (2.26 for males and 0.79 for females). The exposure to asbestos has been defined for 198 mesothelioma cases with histological diagnosis: 125 cases (63%) refer to professional exposure, 10 (5%) to environmental exposure, 5 (2.5%) to domestic exposure. The adoption of a well-constructed national database, the up-date of guidelines and the recent starting up of ReNaM in other italian regions (Lombardy, Veneto, Marche, Campania, Basilicata and Sicily) will shortly lead to obtaining a major representativeness of the Italian situation.