The majority of epidemiological data on cutaneous melanoma (CM) derives from studies carried out in a predominantly fair-skinned population. On the contrary, little is known of the epidemiological figures (including incidence data) in mediterranean populations. The aim of this study was to investigate the incidence rates of CM in a geographically-defined area of the centre of Italy, with particular attention to anatomic site distribution, histologic types and thickness of tumour invasion. After revision of the data base of the Tuscany Cancer Registry concerning the period 1985 to 1987, 282 incident cases of invasive CM (135 males, 147 females) were found in a resident population of 1,174,121 inhabitants. The mean annual age-standardized rates were 6.7/100,000 for males and 7.0/100,000 for females. Site-specific incidence rates showed an almost three-fold higher incidence of CM of the trunk in males than females (3.7/100,000 vs 1.4/100,000). Conversely, a four-fold higher incidence in females than in males was observed for the lesions of lower limb (2.1/100,000 vs 0.5/100,000). A statistically significant difference of incidence rates was also observed for the thigh (females 1.1/100,000, males 0.2/100,000), a normally sun-exposed area. Concerning histologic types of CM, the incidence of the nodular type was higher in males than in females (1.8/100,000 vs 1.3/100,000), even if the difference was not statistically significant in any class of age.(ABSTRACT TRUNCATED AT 250 WORDS)