CONTEXT: Mass violence against civilians in the west of Sudan has resulted in the displacement of more than 1.5 million people (25% of the population of the Darfur region). Most of these people are camped in 142 settlements. There has been increasing international concern about the health status of the displaced population. OBJECTIVE: To perform rapid epidemiological assessments of mortality and nutritional status at 3 sites in South Darfur for relief efforts. DESIGN, SETTING, AND PARTICIPANTS: In August and September 2004, mortality surveys were conducted among 137,000 internally displaced persons (IDPs) in 3 sites in South Darfur (Kass [n = 900 households], Kalma [n = 893 households], and Muhajiria [n = 900 households]). A nutritional survey was performed concomitantly among children aged 6 to 59 months using weight for height as an index of acute malnutrition (Kass [n = 894], Kalma [n = 888], and Muhajiria [n = 896]). A questionnaire detailing access to food and basic services was administered to a subset of households (n = 210 in each site). MAIN OUTCOME MEASURES: Crude and under 5-year mortality rates and nutritional status of IDPs in Kass, Kalma, and Muhajiria, South Darfur. RESULTS: Crude mortality rates, expressed as deaths per 10,000 per day, were 3.2 (95% confidence interval [CI], 2.2-4.1) in Kass, 2.0 (95% CI, 1.3-2.7) in Kalma, and 2.3 (95% CI, 1.2-3.4) in Muhajiria. Under 5-year mortality rates were 5.9 (95% CI, 3.8-8.0) in Kass, 3.5 (95% CI, 1.5-5.7) in Kalma, and 1.0 (95% CI, 0.03-1.9) in Muhajiria. During the period of displacement covered by our survey in Muhajiria, violence was reported to be responsible for 72% of deaths, mainly among young men. Diarrheal disease was reported to cause between 25% and 47% of deaths in camp residents and mainly affected the youngest and oldest age groups. Acute malnutrition was common, affecting 14.1% of the target population in Kass, 23.6% in Kalma, and 10.7% in Muhajiria. CONCLUSION: This study provides epidemiological evidence of the high rates of mortality and malnutrition among the displaced population in South Darfur and reinforces the need to mount appropriate and timely humanitarian responses.