Introduction: Suspicious adnexal masses need to be investigated thoroughly as it may represent ovarian cancer, which is the fourth most common gynaecological cancer in Malaysia. Conventional cross sectional imaging may reveal non-specific findings, thus lead to unnecessary biopsies. 18F-Fluorodeoxyglucose positron emission tomography/ computed tomography (18F-FDG PET/CT) has emerged as a useful tool, for characterization of indeterminate adnexal masses. Most studies have been conducted in Western population, and little information is available in Asian population in general and Malaysian population in particular. Methods: Prospective study of women with suspicious adnexal masses, referred to the Centre for Nuclear Diagnostic Imaging, Universiti Putra Malaysia to undergo pre-operative whole-body contrast-enhanced 18F-FDG PET/CT scans from January 2014 to January 2016. Subjects underwent Contrast-Enhanced Computed Tomography (CECT) scans followed by positron emission tomography (PET) scans using a hybrid scanner. Two radiologists analyzed the CECT and PET/CT images by consensus; blinded to the HPE results. Then the PET/CT findings were correlated with HPE results as the gold standard. Results: 11 whole-body PET/CT scans and 18 adnexal masses (12 HPE-proven malignant lesions and 6 benign lesions) were analyzed. The sensitivity, specificity, PPV, and NPV of CECT alone compared to PET/CT was 91.7%, 50.0%, 78.6%, and 75.0% vs. 91.7%, 100%, 100% and 85.7% respectively. Conclusions: Improved diagnostic accuracy for characterizing benign and malignant adnexal masses can be achieved using contrast-enhanced 18F-FDG PET/CT, making it a potential investigation of choice which can help in treatment planning.