Aqueous and methanol leaf extracts of C. abyssinica and V. sinaiticum were investigated for thernpresence of secondary metabolites, their in vitro and in vivo activity against Trypanosomarncongolence, the main causative agent of African animal trypanosomosis in Sub-Saharan Africa andrnEthiopia. The in vitro assay was carried out by monitoring test concentrations of 4, 2, 1, 0.4 and 0.2rnmg/ml for cessation or reduction in motility of trypanosomes followed by monitoring for loss ofrninfectivity to mice. The in vivo antitrypanosomal efficacy of the extracts was evaluated in Swissrnalbino mice infected with T. congolense field isolate. The leaf extracts were administered 12 daysrnpost-infection at peak parasitaemia level of ~108 trypanosomes/ml at doses of 100, 200 and 400rnmg/kg by intraperitoneal injection once daily for 7 days. Parasitaemia, packed cell volume (PCV),rnmean survival time and change in body weight were used as indices for monitoring the efficacy ofrnthe extracts by comparing with the positive control: 28 mg/kg dose of diminazene aceturate andrnnegative control: 2% tween 80 treated groups. Phytochemical screening revealed presence ofrnalkaloids, anthraquinones, flavonoids, glycosides, phenolic compounds, saponins, steroids, terpenesrnand tannins. An appreciable in vitro activity was attained by the methanol extract of C. abyssinica atrn4 mg/ml concentration which ceased motility of trypanosomes within 30 min and which caused lossrnof infectivity of trypanosomes to mice, which remained aparasitaemic for 21 days after therninoculation of the in vitro mixtures. The extracts had a lethal dose greater than 2000 mg/kg and therernwere no evidences of acute toxicity at the doses tested. Highly significant (p