We analyzed data obtained from 3365 patients with kala-azar (KA) or post-KA dermal leishmaniasis (PKDL) treated by Medecins Sans Frontieres-Holland in south Sudan from October 1998-May 2002. Patients were malnourished (median body mass index [BMI], 15.5; median weight for height [WFH], 75.5%) and anemic (median hemoglobin (Hb) level, 8.5 g/dL). The proportion of patients with primary KA who were children <5 years old increased from 2.5%, in 1998, to 19.8%, in 2002 (P<.0001). Therapy with sodium stibogluconate cured 91.9% of patients with primary KA, and dosages of >850 mg per day did not decrease the chances of survival. Risk factors for death among adults were age > or =45 years (odds ratio [OR], 4.6), malnutrition (BMI, <13; OR, 11.0), anemia (Hb level, <8 g/dL; OR, 4.0), and duration of illness (duration, > or =5 months; OR, 2.3). Risk factors for death among children and adolescents were age <2 years (OR, 5.4,), malnutrition (WFH, <60%; OR, 5.0), anemia (Hb level, <6 g/dL; OR, 3.7), and splenomegaly (OR, 2.9). A higher risk of death was associated with episodes of diarrhea (OR, 1.4), vomiting (OR, 2.7), and bleeding (OR, 2.9). Relapse and PKDL occurred in 3.9% and 10.0% of cases, respectively.