In August 1998, citing a need to control insecurity on their western borders, Rwanda and Uganda sent troops into the Democratic Republic of Congo (DRC) (estimated 2002 population: 51 million). Within 6 months, troops from seven neighboring countries were fighting in the DRC, with various Congolese groups supporting different invading armies. During 1998-2002, the majority of the fighting occurred in the DRC's five eastern provinces (1996 population: 19.9 million). To assess the impact of the armed conflict on public health, the International Rescue Committee (IRC), with support from CDC, conducted a nationwide mortality survey to measure DRC's nationwide crude mortality rate (CMR) and to compare CMRs in DRC's five eastern provinces with CMRs in the five western provinces. This report summarizes the results of the survey, which indicate that the overall CMR in the DRC is the highest in the world, with the majority of deaths caused by preventable infectious diseases. The findings underscore the importance of the ongoing peace process, which appears to have contributed to a decrease in mortality rates in eastern DRC, and highlights the importance of collecting population-based health data regularly during armed conflicts.