The Laboratory of Parasitology of Istituto Superiore di Sanità acts as a coordinating centre for anophelism data collection in Italy, and collaborates with the health local authorities. This specific investigation takes into consideration several areas in the provinces of Grosseto and Siena, focusing attention on the rice fields, which are today the most important anopheline breeding sites in Maremma. The records collected in collaboration with the Department of Environmental Zoology (USL 28 Grosseto), show a high density of A. labranchiae, the potential malaria vector, in the coastal areas of Grosseto province, and a decreased susceptibility to some insecticides. Among the other anopheline species found, only A. atroparvus (the species most present on the inland hills of the provinces of Grosseto and Siena) show a remarkable density.