Nephrolepis cordifolia rhizome (sword fern) juice was investigated for diuretic activity in wistar rats. Different parameters viz. total urine volume (corrected for water intake during the test period), urine concentration of electrolytes such as sodium, potassium and chloride have been evaluated. Rhizome juice of Nephrolepis cordifolia (100 mg/kg), the reference drug, furosemide (20 mg/kg) was administrated orally to male Wistar rats and their urine output was quantitated at several intervals of time after the dose. After single dose of the rhizome juice of Nephrolepis cordifolia, urine output was significantly increased. Increase in urinary levels of Na+, K+ and Cl- was also observed after the administration of rhizome juice.