Background: The present study aimed to investigate the utility and importance of the various parameters of complete blood count panel for benign-malignant differentiation of adnexal masses. Materials and Methods: This retrospective study involved 316 patients with documented benign and 253 patients with malignant adnexal masses who underwent primary surgical treatment at a tertiary referral center. Prior to the study, all benign and malignant cases were compared within their own groups and then the benign and malignant cases were compared to each other. For all cases, cut-off, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated for the neutrophil lymphocyte ratio (NLR), platelet lymphocyte ratio (PLR), neutrophil, lymphocyte, platelet and CA-125 parameters, and the results were compared in regards to the groups. Results: NLR, PLR, neutrophil, CA-125, and platelet values were higher in the malignant compared to the benign cases (p<0.01). The lymphocyte value was lower in the malignant cases (p<0.01). No significant differences were found for basophils and eosinophils (p > 0.05). For CA-125, the sensitivity, specificity, PPV and NPV for all cases were 78%, 62%, 62% and 78%, respectively. For NLR, they were 65.6%, 72.1%, 65.3%, and 72.3%, and for PLR, 48%, 81%, 67%, and 66%. Additionally, the sensitivity and specificity were 55% and 77% for CA-125, 66% and 58% for NLR, and 61% and 58% for PLR in early malignant cases. Conclusions: NLR and PLR appear to be useful methods that can be applied together with CA-125 due to the relatively high sensitivity values for the malign-benign differentiation of ovarian masses. Although the specificity of these parameters is lower than CA-125, especially in cases with early malignant ovarian pathology, their sensitivity being higher is promising for the early diagnosis of ovarian cancer. It can be used to detect ovarian malignancies in the early stages, and it will increase the treatment options and improve survival rates.