Female breast cancer incidence and prevalence in Italy have been estimated by region and vast areas from population-based survival data of breast cancer patients and 1970-1987 specific mortality data using a mathematical model. Italian age-standardized incidence rates (ASR) for 1987 range from 70 to 90 per 100,000 women-year in the Northern regions, 55 to 73 in the Center, and 45 to 72 in the South. Overall, the ASR is about 80 in the North, 70 in the Center and 60 in the South. In the absence of competitive mortality, breast cancer cumulative risk in the 0-74 years life span is about 7 women out of 100 in the North, 6 in the Center and 5 in the South. The decreasing risk pattern from North to Center then South appears less evident when under 45 age-specific rates are considered. Very high levels for young age-groups are present both in the North (Liguria and Emilia Romagna) and South (Sardinia and Apulia). The incidence pattern by age differs from region to region and over the considered period, suggesting that a birth-cohort effect is crossing the whole country. Using to model, it can be estimated that the risk by cohort increases from the generations born at the beginning of the century to those born in the 40s, after which, for subsequent generations, it has been decreasing in all the considered areas and is similar in the North and South. We can infer that for the whole country the incidence will increase up to the years 2000-2010 when those birth-cohorts at higher risk will also be at higher risk for age. In 1987, about 250,000 Italian women had a present or past history of breast cancer: for the 1970-1987 period, prevalence has increased by approximately 5,500 cases per year.