The efficacies of diminazene aceturate alone and in separate combinations with levamisole and Dimethyl Sulfoxide (DMSO) in the treatment of T. congolense infection in rats were assessed on day 7 post infection and days 7 and 14 post treatment using changes in the weights and histology of the liver, spleen, heart and brain as well as parasitemia as parameters. Infected rats were treated with 7.0 mg/kg diminazene aceturate on day 7 post infection following which DMSO (0.5, 1.0 and 2.0 g/kg, respectively) and levamisole (10, 20 and 40 mg/kg, respectively) were administered as daily supplements to different groups of rats. Trypanosoma congolense only caused significant increase in spleen weight. There were no histopathological lesions in any organ. Infection had no effect on heart weight. Liver and spleen weights were lower in the diminazene group by day 7 Post Treatment (PT), but this situation was reversed by day 14 PT. Increase in the dose of DMSO caused increased liver weight. Diminazene/DMSO combination was more effective at 14 days PT in reducing spleen weight than treatment with diminazene alone. On the contrary, diminazene/levamisole combination was less effective than diminazene alone in reducing spleen weight. Parasites disappeared after diminazene treatment but reappeared only in the diminazene and levamisole groups by day 14 PT. Early relapse and high virulence of the Basa strainof T. congolense used may be responsible for the ineffectiveness of the three treatment protocols.