Background: Populations of Gontougo (Côte d'Ivoire) commonly used Euphorbia hirta (Euphorbiaceae) leaves as galactagogue to boost milk production in lactating women. Our study was carried to verify this traditional belief via evaluations of milk production, serum prolactin levels, body weight and mammary lobuloalveolar proliferation induced by the aqueous leaf extract of this medicinal plant in Wistar rats. Methods: 6 groups of 6 virgin rats and 6 groups of 6 lactating rats were used. Each lactating rat was isolated with its six pups. These groups of animals were treated orally with distilled water, Metoclopramide (Metocl 5 mg/kg) and E. hirta aqueous leaf extract (EHae 100, 200, 400 and 600 mg/kg) daily during 17 days of lactation. The indirect method which assimilates the weight gain of untreated pups to the quantity of milk produced by lactating rats was used. At the end of the treatment, histological sections of the abdominal mammary glands of lactating rats were observed. Results: EHae administration induced an increase of milk production in lactating rats. This action of EHae was stronger at the dose of 200 mg/kg. Milk production of the treated rats at a dose of 200 mg/kg was 118.14 ± 1 g. The quantity of milk produced by the control female rats was 83.83 ± 0.88 g. Compared with the control, EHae 200 mg/kg significantly increased milk production (40.92%) (P < 0.0001). EHae 200 mg/kg significantly increased the biosynthesis of prolactin (PRL) in virgin rats (P < 0.0001). At this dose, PRL values measured at D7 and D14 were 26.44 ± 8.64 and 33.88 ± 7.30 ng/ml respectively, whereas the value obtained in the controls that received distilled water was less than 0.5 ng/ml. Histological analysis showed that EHae 200 mg/kg induced the development of the lobuloalveolar system of the mammary glands. Conclusion: EHae showed a galactagogue activity illustrated by increases of milk production, PRL secretions and the development How to cite this paper: .79006 52 Journal of Biosciences and Medicines of the lobuloalveolar system of the mammary glands in treated female rats. This galactagogue property could partly justify the traditional use of this plant to boost milk production in lactating women.