We report a case of polypoid endometriosis of the ovary and correlate magnetic resonance (MR) and pathologicalˆndings. The endometriosis appeared as multiple polypoid areas along the wall of the ovarian cystic lesion with hyperintensity on T 2 -weighted images and slight hyperintensity on diŠusion-weighted images. However, the polypoid areas did not yield low apparent diŠusion coe‹cient (ADC) values on ADC map images. These MRˆndings were similar to the signal intensity of the uterine endometrium, re‰ect-ing the presence of abundant endometrial glands.