Many countries have reported an increase in breast cancer incidence in young women. The current study's objective was to explore breast cancer distribution in women less than 50 years of age in Brazil. A descriptive study on breast cancer incidence (selected cities) and mortality (Brazil and selected cities) in 2002-2004 was carried out, and the results were compared with those from other countries. The study also analyzed the trend in hospital morbidity and incidence rates for breast cancer. Porto Alegre (Rio Grande do Sul State) showed the highest incidence rates (17.9 and 165.5/100,000 in the 15-39 and 40-49-year age strata, respectively). Regarding mortality, Belo Horizonte (Minas Gerais State) showed the highest rate in the 15-39-year group and Porto Alegre in the 40-49-year group (2.8 and 25.5/100,000). Hospital admissions and incidence rates for breast cancer suggest a change in epidemiological distribution. The results reveal an epidemiological pattern of breast cancer in young Brazilian women with regional distribution characteristics.