Mucuna pruriens is used extensively for its medicinal value for the treatment of diabetes mellitus in Nigeria. This study investigated the anti-diabetic activity of Mucuna pruriens on the blood glucose levels and the histopathology of the pancreas. To achieve this, Acute toxicity studies of the plant extract was determined. Doses of 100, 200 and 400mg/kg bw of the extract were administered orally daily for 21 days to alloxan-induced diabetic Wistar rats. Metformin was used as a standard anti-diabetic drug and given by gavage. The fasting blood glucose levels were determined at intervals of three days. Premininary phytochemical screening revealed the presence of flavonoids, saponin, tannins, cardiac glycosides, triterpenes and reducing sugars. The LD_50 of the extract of Mucuna pruriens was found to be 2154mg/kg. The study showed that there was a significant reduction (p＜0.05) in the fasting blood sugar levels in alloxan-induced diabetic treated groups that received 100, 200 and 400mg/kg of the extract orally, with a maximum reduction (p＜0.01) of 161.83±18.2, 153.67±13.8 and 133.83±10.4 recorded in the groups treated with 100, 200 and 400mg/kg. The histopathological studies of the pancreas of diabetic animals revealed the degeneration of pancreatic Islet cells, but with the restoration of pancreatic Islet cells in the pancreas of diabetic group treated with various doses of the plant extract. The implications of the results obtained in the present study provide the scientific rationale for the use of Mucuna pruriens as anidiabetic agent.