Trypanosomosis is a widespread and important disease of animals and humans in tsetse-infested areas of Africa, Nigeria inclusive. To investigate the comparative effects of graded doses of Diaminazine aceturate (DA) and fixed doses of Levamisole in the treatment of albino mice experimentally infected with field isolates of Trypanosoma brucei brucei. Thirty adult mice were used and were randomly divided into 6 groups of 5 mice each. After infection has been established, 3 groups (A, B and C) were treated with graded doses of DA at 7, 14 and 21mg/kg body weight respectively and a fixed dose of Levamisole at 7.5mg/kg body weight, whereas group D was treated with Levamisole only at the same dose.  Group E served as positive (infected untreated) control while group F served a negative (uninfected untreated) control. The following parameters were used to access the efficacy of the drugs: weekly rectal temperature, weight changes, packed cell volume, haemoglobin concentration, clinical signs or survivabilty and parasitaemia. The parasite cleared from groups A, B and C by the 48th hour post treatment, but remained in group D while all the mice in group E died within 65 days PI, those in group D died within 65 days PI, whereas those in Group D died within 35 days post treatment. Relapse infection was only recorded in group A at day 30 post treatment. There was no relapse in group B and C, but more deaths were recorded in group C. The significant reduction (p<0.05) in the weight, PCV and haemoglobin concentration and an increase in rectal temperature following infection was reversed by the treatments in groups A, B and C. The results obtained show that an increased dose of DA at 14mg/kg body weight and Levamisole at 7.5mg/kg body weight proved most effective in the treatment of clinical cases of infection with Trypanosoma brucei brucei.