Sex cord tumor with annular tubules (SCTATs) is a relatively rare ovarian neoplasm often having a syndromic association with Peutz-Jeghers syndrome (PJS). Other associations described with this rare neoplasm include adenoma malignum of cervix, Turners syndrome, dysgerminoma, gonadoblastoma, endometrial carcinoma, and endometriosis of fallopian tube. We describe for the first time to the best of our literature search the incidental detection of SCTAT coexisting with an endometriotic cyst of ovary. Meticulous histological scanning and awareness is mandatory for detection of such unusual incidental lesions. Non-PJS SCTATs tend to be larger and could be more prone to distant metastasis, warranting subsequent follow-up.