Objective To explore the effects of raloxifene on pituitary gland in rats. MethodsOvariectomized Wistar female rats were implanted with silastic tubes containing raloxifene, 17-β estradiol or blank silastic tube alone, respectively. After 8 weeks, all the rats were weighed and sacrifieced. The pituitary glands were collected and weighed. Serum prolactin level (PRL) was tested by solid phase-sandwich method. ResultsThere was no significant difference between the pituitary weights of the raloxifene and control groups. However, the pituitary weight of the estrogen group was significantly higher than that of raloxifene and control groups. (both P <0.05). The serum PRL level in the estrogen group was significantly higher than that in the raloxifene and control groups (both P<0.05). The serum PRL level of the raloxifene group was significantly higher than that of the control group (P<0.05). The serum PRL level in the raloxifene group was significantly lower than that of the estrogen group (P<0.05). Histological examination showed normal pituitary morphology in the raloxifene and control groups, but characteristic changes of prolactinoma were seen in the pituitary gland of estrogen group. ConclusionRaloxifene has a certain impact on rat pituitary gland, but does not induce prolactinoma.