Abstract Mucinous ovarian carcinoma (MOC) is a rare, chemoresistant tumor that shares pathologic features with tumors of the gastrointestinal and pancreaticobiliary tracts and remains clinically, morphologically, and epidemiologically distinct from other more common ovarian cancer histologic subtypes. MOC accounts for 1-8% of all ovarian, typically affecting younger women and has a poor prognosis when disease has spread beyond the ovary. Unlike other epithelial ovarian cancers, increased risk of MOC is associated with cigarette smoking in a dose-dependent fashion. Oral contraceptive use that has been shown to be protective in serous ovarian cancer does not extend to MOCs. Despite clinical, pathologic, and epidemiologic differences from other epithelial ovarian cancers, MOC treatment continues to use standards defined for high grade serous ovarian cancer including comprehensive surgical staging followed by platinum and taxane combination chemotherapy for disease spread beyond the ovary. Most mucinous adenocarcinomas that involve the ovary are now recognized to be metastatic disease from an extraovarian site, most commonly gastrointestinal and pancreatic. In advanced stage cases, defining clear diagnostic criteria that reliably differentiates primary versus malignant tumors remains a challenge. Despite a similar site of origin, the molecular profile of MOC has few similarities to high-grade serous ovarian carcinoma, which is characterized by ubiquitous TP53 mutations, frequent BRCA1/2 mutations, and few KRAS mutations. The mutational landscape of MOC is characterized by frequent KRAS, TP53, ARID1A, and PIK3CA mutations as well as frequent CDKN2A homozygous deletions. Co-mutations of KRAS and TP53 are common. New data describe the molecular features of MOC using an integrative and comprehensive approach including next-generation sequencing, copy number analysis and immunohistochemistry that may lead to expanded treatment options for women with this rare disease. Data suggest a shared molecular pattern with pancreatic adenocarcinoma that may guide future therapeutics. Citation Format: Douglas A. Levine, Brooke Schlappe. Molecular characterization of mucinous ovarian carcinoma. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: Exploiting Vulnerabilities; Oct 17-20, 2015; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(2 Suppl):Abstract nr IA17.