Animals were treated with alcoholic and aqueous extract of Cassia fistula at a dose level of 400mg/kg bodyweight by standard methods. Blood glucose, glycosylated hemoglobin, triglyceride, LDL, VLDL,HDL, blood urea and cholesterol were measured at the beginning and at the end of the experiment. The extracts have shown potential activity in decreasing the serumglucose level and other complications associated with experimental diabetes. The extracts also showed significant hypoglycemic effect in fasted normal rats (P<0.01). The present study reveals that the bark of Cassia fistula is very promising for developing standardized phytomedicine for diabetes mellitus. Thus the present study supports the traditional claim of the plant for the ailment of various diabetes associated complications.