The limited scientific knowledge on the relationship between exposure and health effects in relation to geothermal activity motivated an epidemiologic investigation of Tuscan geothermal area. This study aims at describing mortality of populations living in Tuscan municipalities in the period 2003-2012. Sixteen municipalities were included in the study area, eight in the Northern and eight in the Southern Area. Mortality data come from the Regional Mortality Registry of Tuscany. Fifty-four causes of death, considered of interest for population health status or consistent with "Project SENTIERI" criteria, are analyzed. Results show a worse mortality profile in the Southern area, especially in males, for whom excesses of all cancers and some causes of cancer emerge, while in the Northern Area an excess of cerebrovascular diseases among females merits attention. Further and more appropriate studies are needed to clarify the etiology of some diseases and to better assess a potential cause-effect relationship.