The present study is involved with the prolactin secretion from anterior pituitary gland by ginseng saponin since it was handled down by tradition that ginseng might influence the milk secretion when it was given to nursing mother. To investigate the effect of saponin on the prolactin production or release from the anterior pituitary gland, cell culture study and whole animal studies were carried out. For the cell culture study, enzymatically dispersed anterior pituitary cells of rat anterior pituitary gland in HEPES buffers containing trypsin were used. Ginseng saponin was added to the culture media and the amount of prolactin produced in the cell culture media was determined by radloimmunoassay(RIA) technique. Dose-dependent increases of prolactin with ginseng saponin were observed, whereas, no change was observed without ginseng treatment. For the whole animal study, normal and castrated rats which previously cannulated into the heart via the right juglar vein were used. The prolactin concentration in plasma were determined by using the technique of RIA. In normal rats, prolactin concentration in plasma were elevated dramatically after 1 hour of ginseng saponin administration, whereas, instantaneous increases were observed in castrated rats. For prolactin assay by RIA, NIAMDD Rat Prolactin Kit and NIAMDD Rat Prolactin RP-1 were used as standard. The results indicate that ginseng saponins increase the release of prolactin from the anterior pituitary gland and production of prolactin from the cell in rats.