The effect of subchronic administration of ethanolic stembark extract of Mammea Africana
(30 - 90mg/kg) on haematological and biochemical parameters of rats was studied. Significant decreases in activities of serum alkaline phosphatase (ALP), Aspartate aminotransferase (AST) and Alanine aminotransferase (ALT) as well as decreases in the levels of serum total protein and albumin were observed in the extract treated rats compared to control. White Blood Cell counts of the extract treated rats also decreased significantly while other haematogical parameters were unaffected. Thus, the extract has a slight toxicity at the doses studied.