Brazil is the largest and most populous country in South America (2002 population: approximately 175 million) (Brazilian Geography and Statistics Institute [BGSI], unpublished data, 2004). Although life expectancy in Brazil has increased and rates of infant mortality have decreased as a result of reductions in infectious disease mortality, homicide and other forms of injury-related mortality have increased as a proportion of overall mortality. Homicide is now the leading cause of death for persons aged 15-44 years. To describe trends and characteristics of homicides countrywide and in Sĕo Paulo city (2000 population: approximately 10.4 million) (BGSI, unpublished data, 2004), the State Health Department of Sĕo Paulo (SHDSP) analyzed vital statistics and census data for 1980-2002. This report summarizes the results of that analysis, which indicated that the homicide rate in Brazil more than doubled during this period. Since 2001, Brazilian authorities have implemented several initiatives to reduce the number of homicides, including a law that controls gun ownership and prohibits anyone other than police and members of the armed forces from carrying guns. However, homicides among adolescents and young adults remain a substantial public health problem in Brazil, and additional prevention strategies that target young persons are needed.