Abstract: This research was undertaken to determine the effects of the extract of Vernonia amygdalina on some biochemical parameters in rat. The ethanol extract of leaf of Vernonia amygdalina was administered daily orally to four groups of rats at a dose of 100, 250, 500 and 1000 mg kg-1 weight, respectively, for 28 days. On the 29th day blood was obtained from the hearts of the rats. The blood samples were centrifuged to obtain the blood serum.Serum levels of the following enzymes and biomolecules were evaluated: alanine and aspartate transaminases, alkaline phosphatase, glucose, creatinine, proteins, total and conjugated bilirubin, total cholesterol, triglycerides, high density lipoproteins, low density lipoproteins and very low density lipoproteins. Weights of the animals were taken weekly. The results of this study show that the extract reduced significantly the levels of glucose by 15.6, 23.4, 19.5 and 11.7% at 100, 250, 500 and 1000 mg kg-1 doses, respectively. While only 250 mg kg-1 of the extract also decreased the value of triglycerides (1.0331 mmol L-1) compared to control (1.687 mmol L-1). It can be concluded from these results that the leaf extract of Vernonia amygdalina is safe for use in ethnomedicine, especially in ethnotherapy of diabetes mellitus.