Abstract: Objective: To analyze the clinicopathologic features of 5 cases with uterine placental site trophoblastic tumors (PSTT) to enhance the quality of the diagnosis and treatment. Methods: Fivecases with PSTT were studied through clinical, microscopic and immunohistochamistical observation.Results: PSTT usually occurred in women at reproductive age, in which 3 cases were hydatidiform moleand 2 cases were term- delivery in previous pregnancy. Most patients complained irregular vaginalbleeding. Before operation the serum level of β - hCG elevated from 725 IU/L to 2240 IU/L normal val-ue<20 IU/L). Under microscopic observation. The tumor cells all originate from implanatation- site inter-mediate trophoblastic cell ( IT ), Which arranged into nests and cords often infiltrated into smooth mus-cle fibres and blood vessel's wall of uterus, Mitotic figures<2/10HPF or null, immunohistochemical tests revealed postive staining for hPL and negative staining for hCG. We should distinguish PSTT withnormal pregnancy placental bed, exaggerated placental site placental site nodule and plaque. Chorioep-ithelioid carcinoma, epithelioid trophoblastic tumor. Conclusion: PSTT is composed by implanation-site intermediate trophoblastic cell. Most PSTTs are of benign biological behavior. All the 5 cases arefollowed- up in 1-16 years and all are alived.