Aim: To determine the effect of the aqueous extract of Mondia whitei (Periplocaceae) roots on testosterone production and fertility of male rats. Methods: Adult male Wistar rats were used. In the acute study, 20 rats were randomly divided into 5 groups of 4 animals each. Four treated groups were administered orally a single dose of Mondia whitei (400 mg/kg) and the controls received a similar amount of distilled water. One group of animals were sacrificed by cervical dislocation 1,2,4 and 6 h after treatment, respectively. The controls were sacrificed at 6 h. Testicular testosterone was determined by radioimmunoassay. In the chronic study, 28 rats were divided at random into 4 groups of 7 animals each: Groups 1, 2 and 3 were given orally the plant extract (400 mg·kg-1·day-1) for 2, 4 and 8 days, respectively. The animals of Groups 1 and 2 were sacrificed 24 hours after the last dosing. The controls (Group 4) received the same amount of distilled water for 8 days. The fertility was assessed only in Grou Method: adult male Wistar rats were used. In the acute study, 20 rats were randomly divided into 5 groups of 4 Animals each. Four treated groups were administered orally a single dose of Mondia whitei (400 mg/kg) and the controls received a similar amount of distilled water. One group of animals were sacrificed by cervical dislocation 1,2,4 and 6 h after Treatment, respectively. The controls were sacrificed at 6 h. Testicular testosterone was determined by radioimmunoassay. In the chronic study, 28 rats were divided at random into 4 groups of 7 animals each: Groups 1, 2 and 3 were given orally the plant extract (400 mg·kg-1·day-1) for 2, 4 and 8 days, respectively. The animals of Groups 1 and 2 were sacrificed 24 hours after the last dosing. The controls (Group 4) received the same amount of distilled Water for 8 days. The fertility was as Sessed only in Grou