<正> Objective: To report two recent cases of pituitary adenoma associated with Toxoplasma gondii （T. Gondii） infection. Methods: Histological changes were observed in H & E and PAS staining sections microscopically. Immuno-histochemistry was performed to classify the pituitary tumors and to confirm the diagnosis of T. gondii. Results; The cases were 43- and 19-year-old females

in which the latter one was a recurring case

and radiology examination showed that tumors existed in sellar region. Microscopically

the tumors consisted of small homogenous polygonal or round cells with abundant eosinophilic granular cytoplasm. Immunohistochemistry revealed they were prolactin-producing adenomas. Interestingly

we found toxoplasma infection in the tumor tissues

being confirmed by T. gondii sepicific antibody immunohistochemistry. Conclusion: The association of pituitary adenoma with toxoplasma raises the possibility that T. gondii may be involved in the development of certain cases of pituitary adenoma.