The present study was undertaken to investigate the diuretic activity of Rumex vesicariys.Linn and its formulation in experimental rats. The preliminary phytochemical investigation was carried out to identify the various chemical constituents present in the alcoholic extract. It was found that the Rumex vesicarius contain carbohydrate, glycosides, saponin, steroids, and flavonoids and anthraquinones. The diuretic properties of Rumex vesicarius were evaluated by determination of urine volume, electrolyte concentration,diuretic activity,diuretic action and saluteric index in male albino rats. Different concentrations of Rumex vesicarius benzene and ethanol extract (750mg/kg, 1000mg/kg) were orally administered to hydrated rats & their urine output was immediately measured for 6 hours of treatment. Frusemide (0.10mg/10g) was used as reference drug while Tween 80 solution was used as control. Rumex vesicarius exhibited dose dependent diuretic property. The onset of diuretic action was extremely prompt (with in 1 hour) are lasted through out the study period (up to 6 hours). The result suggests that the ethanol extract (1000mg/ml) of Rumex vesicarius.Linn possess significant diuretic activity.But the formulation(syrup) shows less activity than the Ethanol extract (1000mg/ml),it may be due to the sugar base which is interfering in the urine excretion.