RESUMEN
The possible diuretic effect of the leaf extract of Cecropia obtusifolia, Bertol; used in Costa Rican traditional medicine, was tested on five Sprague Dawley rats in individual metabolic cages. During the control week, distilled water was administered with an intragastric cannula. During the C. obtusifolia week, the rats were given the aqueous leaf extract in a daily dosage of 500 mg/kg, intragastricly. Although, the urinary flow was increased (p < 0.05) by a 20 per cent, there was no statistically significant difference between the following parameters: excretion in urine of osmoles, sodium and potassium; daily ingestion of food and water. The animal weights decreased when C. obtusifolia was used, but only on the fourth day the decrease was significant (p < 0.05). In conclusion, the aqueous leaf extract of C. obtusifolia has a slight diuretic effect.