All parts of the plant Benincasa hispida is traditionly used in different diseases because of their medicinal properties. The endocarp and rind of the fruit is diuretic. The present study was carried out to evaluate the diuretic effect of ethanol extract of Benincasa stem (EEBCS) in rats in comparison with standard drug Hydrochlorothiazide. Forty five male Swiss albino rats aged ten to twelve weeks of male sex weighing about 175–200 g were taken, and after acute toxicity studies three different doses were selected. The animals were divided into five different groups. The first group was kept as the control (Normal Saline), second as the standard (Hydro chlorthiazide) and the remaining three groups as Test I, Test II, and Test III and given different doses of the EEBCS. Diuretic and Natriuretic activities were carried out by administration of normal saline along with the treatment modules. The volume of urine (in ml) and the Na+, K+ and Cl-content in the urine were measured. The results were expressed as mean ± SD. Statistical analysis was carried out by using ANOVA followed by Dunnet’s multiple comparison tests using primer of biostatistics McGraw–Hill software version 5.0.0.0 (2011). P-values < 0.05 were considered significant. The extract at 100 and 200 mg / kg, produced significant diuresis and increased sodium elimination but not potassium. Thus the study elucidates that aqueous extract of Benincasa stem possess significant diuretic, Saluretic, Natriuretic and carbonicanhydrase activity.