The aim of this study was to assess the incidence of breast cancer in women from the city and province of Palermo (Sicily) in 5 yr, 1999-2003, using a population based cancer registry approach. In the last years, a sharp increase of breast cancer incidence has been observed worldwide. Overall, direct age-standardized incidence rates were 89.3 per 100,000 person-yr, being markedly higher in Palermo City (101.0) than in Palermo Province (75.0). Results show a highly significant difference in breast cancer incidence in different areas of Sicily, particularly in the older (>50 yr) age groups and a profound difference between the metropolitan area of Palermo and the surrounding areas. The evidence of the different rates of breast cancer incidence in Palermo City and in the other small municipalities of the Palermo Province suggests a different pattern of breast cancer risk as a consequence of different lifestyle and diet modifications in the urban population of Palermo City.