Diuretic, hypotensive and hypoglycaemic effects of Phyllanthus amarus (syn. Phyllanthus niruri) on human subjects were assessed. Nine mild hypertensives (four of them also suffering from diabetes mellitus) were treated with a preparation of the whole plant of P. amarus for 10 days. Suitable parameters were studied in the blood and urine samples of the subjects, along with physiological profile and dietary pattern before and after the treatment period. Significant increase in 24 hr urine volume, urine and serum Na levels was observed. A significant reduction in systolic blood pressure in non-diabetic hypertensives and female subjects was noted. Blood glucose was also significantly reduced in the treated group. Clinical observations revealed no harmful side effects. These observations indicate that P. amarus is a potential diuretic, hypotensive and hypoglycaemic drug for humans.