Sauropus androgynus is traditionally consumed by Indonesians and is believed to increase breast milk production during lactation. Lactation, a process of milk synthesis and secretion, occurs with the help of 2 hormones, prolactin and oxytocin. The expressions of genes encoding prolactin and oxytocin were analyzed in lactating BALB/C mice brains using qRT-PCR. A total of 24 lactating BALB/C mice were fed with experimental diets for 12 days. Two groups of lactating mice were fed with diets containing either young or mature S. androgynus leaf extracts. For the control, one group of lactating mice was fed a diet without S. androgynus leaf extracts. Supplementation of young S. androgynus leaf extracts increased the expression of prolactin and oxytocin genes in lactating mice 9.04- and 2.25-fold, respectively. Meanwhile, supplementation of mature S. androgynus leaf extracts increased the expressions of both genes 15.75- and 25.77-fold, respectively, compared to the control group. The result suggested that mature S. androgynus leaf extracts significantly increased the expressions of both genes in lactating BALB/C mice and was predicted to correlate with papaverine content, which is only detected in mature S. androgynus leaves at a concentration of 0.38 ± 0.04 µg·ml^–1.