OBJECTIVE: To investigate the diuretic, natriuretic and kaliuretic effects of the antihypertensive Ayurveda drug Karavi Panchaka decoction and compare it with the diuretic frusemide. DESIGN: An animal study using Sprague-Dawley rats. The volume of urine and the total sodium and potassium excreted in the urine by rats in response to orally fed Karavi Panchaka decoction were compared with rats fed with frusemide. Control experiments were done with rats receiving similar volumes of distilled water orally. The Ayurveda drug was prepared in accordance with the traditional method in the laboratory using medicinal plant specimens individually collected and identified. MEASUREMENTS: The volume of urine excreted during a 24-hour period following administration of the Ayurveda drug, frusemide or water was measured. The total sodium and potassium ion concentrations in the urine samples were determined using flame photometry. RESULTS: The Karavi Panchaka decoction clearly showed a statistically significant increase in urine excretion when compared with the control group that received only distilled water. The potassium ion excretion was significantly increased in the Karavi Panchaka decoction treated group when compared to the control group. This increase was statistically similar to that caused by frusemide. Neither drug had a significant effect on sodium ion excretion at the dosages used. CONCLUSION: Our results show that the Karavi Panchaka decoction significantly increases urine and potassium ion excretion in rats, but has no effect on sodium ion excretion at the dosage used. The effect of the Ayurveda drug on urine output as well as the sodium and potassium ion excretion is similar to that of frusemide administered at the dose used in our study.