Abstract: Objective: To study the preventive effects of chinese medicine, Jiangrusan, and two kinds of dopamine receptor agonists, Norprolac and Pergolide, on Diethystilbestrol （DES） induced rat prolactinoma. Methods: forty six adult Wistar rats, ovariectomized, were divided into 5 groups at random. Each rat in E （n =10）, D₁ （n =9）, D₂ （n =10） and D₃ （n =7） group was subscutaneously implanted with a DES implant. Rats in control group （C group, n =10） were implanted with blank implants. Meanwhile Norprolac, Pergolide or Jiangrusan was orally adimnstrated to rats in D₁, D₂ or D₃ groups respectively. After 8 weeks, all the animals were executed. Each pituitary gland was weighed and collected for histopathological and immunocytochemical examination. Serum prolactin （PRL） levels were measured by RIA method. Results: The weights of pituitary gland, PRL immunoreactive cell countings and serum PRL levels in E, D₁, D₂ or D₃ group were individually greater than those in C group （P ＜0 001 respectively）. Conclusion: Norprolac, Pergolide and Jiangrusan all have potential prevenive effects on estrogen induced rat prolactinoma. The decrease of dopamine contents in hypothalamas may be involved in the pathogenesis of estrgen induced rat prolactinoma.