Abstract: Despite the fact that Anogeissus leiocarpus has been in use for many decades in the treatment of many illnesses little is known about its phytochemistry and toxicological effect in mammals. This study sought to quantitatively determine its phytochemical constituents and its sub acute toxicological effects at certain doses with a view to recommending continual usage of the plant bark at a define concentration or otherwise and to suggest further research based on the outcome. The concentration of saponins was found to be higher (89.5 mg/100 g) than all other phytochemicals where as that of Glycosides were found to be the least (1.7 mg/100 g). Concentration of alkaloids, tannins, steroids, flavonoids and phenols were 26.7, 29.9, 10.6, 27.3, 5.2 mg/100 g, respectively in the aqueous extract. The activities of Alanine Amino Tranferases (ALT), Aspartate Amino Transferase (AST), Alkaline Phosphatase (ALP) and levels of total and direct biluribin were not significantly higher (p<0.05) in all the groups administered with dosage of up to 200 mg kg-1 b.wt. of the aqueous extract of the bark. However, the studies showed that the bark extract results in no liver toxicity and that is safe for consumption at a dose of up to 200 mg kg-1 b.wt.