BACKGROUND: Epithelial ovarian cancer commonly presents with vague symptoms that delay diagnosis until disease is advanced. Granulomatous peritonitis is a term used to describe granulomatous inflammation within the peritoneal cavity and mimics advanced stage ovarian cancer clinically and on imaging. The goal of this study was to examine the frequency and characteristics of cases of granulomatous peritonitis mimicking ovarian cancer at a single institution and to describe the etiology in this population. METHODS: Eight cases were identified with pathology conformation of granulomatous disease and absence of cancer. The etiologies include pelvic tuberculosis, ruptured dermoid cyst, ruptured hemorrhagic corpus luteum, prior endometriosis surgery, xanthogranulomatous inflammation and three cases of tubo-ovarian abscesses. RESULTS: Seven of the eight had pelvic masses on imaging studies; one patient had presumed carcinomatosis without an adnexal mass on CT scan. Preoperative CA-125 was elevated in four of the eight patients, with a range of 30.8 to 228 U/mL. All had some form of surgical management with at least one ovary removed. CONCLUSION: Clinicians should be aware of this disease to improve diagnosis and direct appropriate patient management.