OBJECTIVE: To evaluate mortality and morbidity among internally displaced persons (IDPs) who relocated in a demographic surveillance system (DSS) area in western Kenya following post-election violence. METHODS: In 2007, 204 000 individuals lived in the DSS area, where field workers visit households every 4 months to record migrations, births and deaths. We collected data on admissions among children < 5 years of age in the district hospital and developed special questionnaires to record information on IDPs. Mortality, migration and hospitalization rates among IDPs and regular DSS residents were compared, and verbal autopsies were performed for deaths. FINDINGS: Between December 2007 and May 2008, 16 428 IDPs migrated into the DSS, and over half of them stayed 6 months or longer. In 2008, IDPs aged 15-49 years died at higher rates than regular residents of the DSS (relative risk, RR: 1.34; 95% confidence interval, CI: 1.004-1.80). A greater percentage of deaths from human immunodeficiency virus (HIV) infection occurred among IDPs aged > or = 5 years (53%) than among regular DSS residents (25-29%) (P < 0.001). Internally displaced children < 5 years of age did not die at higher rates than resident children but were hospitalized at higher rates (RR: 2.95; 95% CI: 2.44-3.58). CONCLUSION: HIV-infected internally displaced adults in conflict-ridden parts of Africa are at increased risk of HIV-related death. Relief efforts should extend to IDPs who have relocated outside IDP camps, particularly if afflicted with HIV infection or other chronic conditions.