Placental site trophoblastic tumor(PSTT) is a very rare form of gestational trophoblastic disease; weencountered two cases. MR imaging of the first patient revealed a solid uterine mass, slightly hyperintense tonormal myometrium on T1-weighted images and hyperintense on T2-weighted images. After intravenous gadoliniuminfusion, the mass was more enhanced than normal myometrium, and PSTT was confirmed pathologically after totalhysterectomy. In the second patient, PSTT was proven pathologically after laparoscopic left adnexectomy and wedgeresection of the right ovary. Postoperative enhanced CT scans revealed a well-enhanced right ovarian mass andextensive metastasis to the liver, pancreas, both adrenals, the stomach, lung and brain, but no mass was detectedin the uterus. Many of these metastatic lesions were infiltrating low density masses associated with highlyenhanced tubular or serpiginous structures, while some were of very high density.