OBJECTIVE: To study the lactagogue effect of Rutong granule on rat with postpartum hypogalactia. METHODS: Female rats which had kittening behavior within 24 h were selected to induce rat model by perfusing bromocriptinum. Meanwhile, model rats were given Rutong granule via i.g. gtt. Milk yield of female rats and body weight of young rats were determined everyday from the second day. Rats were sacrificed on the 8th day. The level of PRL and histological change of breast were observed. RESULTS: Rutong granule can increase the serum PRL level gradually to promote the increase of acinar number and dilatation of gland ducts. Rutong granules can also increase the milk yield of female rats and weight of young rats. CONCLUSION: Rutong granule can promote secretion of milk by means of increase of PRL level and expediting of secretion channels.