Tremolite asbestos in rocks surfacing by natural ground erosion as well as originating from construction activities in the Upper Susa Valley (Piedmont, Italy) was recently reported. We investigated the spatial distribution of cases of pleural (ICD Rev 9 163) and peritoneal cancers (ICD Rev 9 158.8 and 158.9) in that area. Mortality and hospital discharge statistics were analyzed by municipality of residence respectively for the periods 1980-98 and 1995-99. Kernel and empirical bayesian estimators of standardized proportional mortality ratios (SPMR) were computed in circular areas of 25, 50, 75, and 100 km distance from Sauze d'Oulx. Pleural and peritoneal malignancies were found to occur in excess in this town and in the surrounding municipalities. A survey is being undertaken to identify cases, verify diagnoses, and assess occupational and environmental exposures.