Objective and background: Malus sylvestris Linn are a plant widely used as a traditional medicinal herb has a wide range of Pharmacotherapeutic activities. The current study was carried out to investigate the diuretic activity of Malus sylvestris Linn fruit aqueous extract (AEMS) in experimental animals. Methods: In the current study Wister rats were divided into 5 groups of n=6 each using Furosemide (100 mg/kg, p.o) as the standard drug and normal saline as the control. AEMS is given at the doses of 200 mg/kg, 400 mg/kg and 800 mg/kg p.o. in distilled water respectively. Lipchitz method was used for his study. Parameters such as volume of urine, concentration of sodium and concentration of potassium are noted. Results and discussion: The study revealed that extract of AEMS has considerably increased the urine volume with significant increase in cationic concentration at increased doses. The concentration of Na+/K+ indicates the dose dependent response with the comparable results at the doses of 200 mg/kg, 400 mg/kg and 800 mg/kg with reference with the standard administered. Oral administration of AEMS at the dose of 800 mg/kg shows high significance (P<0.001) with that of control and dose of AEMS of 400 mg/kg shows significance (P<0.05) shows and dose of AEMS of 200 mg/kg shows less significance (P<0.01) with decreased urine output with that of control. Conclusion: As a result of foregoing study aqueous extract of Malus sylvestris Linn fruit has considerable diuretic activity at higher doses.