The size and duration of the 2000 outbreak of Sudan Ebola virus (SEBOV) infection in Uganda made it possible to collect serial serum samples from 87 patients (53 survivors and 34 nonsurvivors). Surprisingly, the levels of tumor necrosis factor- alpha and interferon (IFN)- gamma , which had been found to be increased in patients with fatal Zaire Ebola virus infection, were not increased in any of the patients with SEBOV infection. The levels of interleukin (IL)-1 beta , IFN- gamma -inducible protein-10, and RANTES (regulated on activation, normally T cell-expressed and -secreted) were higher in samples from all patients with SEBOV infection than in control samples from healthy hospital staff members, but their levels did not differ between those who survived and those who did not. The levels of IFN- alpha were significantly higher in surviving patients with SEBOV infection, whereas the levels of IL-6, IL-8, IL-10, and macrophage inflammatory protein-1 beta were higher in patients with fatal SEBOV infections.