Present investigation was undertaken to evaluate antihyperglycemic, activity of ethanolic extract of Mangifera indica leaves in alloxan induced diabetic rats. Alloxan produced a significant increase in serum glucose, creatinine, urea, uric acid, ALT, AST levels. Treatment with Mangifera indica extract produced decrease in alloxan induced glucose, urea, uric acid, and creatinine levels. There was a significant decrease in total protein, haemoglobin, body weight, albumin and globulin. Administration of Mangifera indica to diabetic rats reduced the effect of alloxan and increased the levels of above parameters. The results suggest Mangifera indica to be beneficial for the treatment of diabetes mellitus.