We have examined the cumulative effects of the protoberberine alkaloidal fraction (AF) of the stein bark ethanolic extracts of Enantia chlorantha on some body tissues and organs as well as on certain biochemical and metabolic parameters in mice. Acute and sub-chronic toxicity studies of the alkaloidal fractions of Enantia chlorantha were carried out in 120 mice using oral and intraperitoneal administrations. Fatality was not recorded in mice injected intraperitonealy with 100 mg kg(-1) and 150 mg kg(-1) dose level but larger doses resulted in death and the mean lethal dose (LD50) toxicity studies showed neither behavioural/untoward reactions nor death in any of the animals. The histopathological examination of the test animals when compared with the control revealed that, the sub-chronic use of the alkaloidal fractions does not have any pathological effects (lesion) on the organs examined (the stomach, the kidney, the oesophagus and the liver) except the lungs which showed mild and moderate oedema. The biochemical and metabolic analysis of the mice plasma did not show any significant difference when the corresponding values for the test mice were compared with the control mice (P > 0.05) at the end of the 14 days treatment using both 20 mg kg(-1) and 2 mg kg(-1) dose levels. The results obtained in this study suggest the relative safety of short-term use of preparations containing E. chlorantha, a very popular antimalarial herbal remedy in Southern Nigeria.