Background: Systematic lymphadenectomy is useful for accurate staging of early-stage ovarian cancer and has obvious prognostic value. Accurate staging may prevent unnecessary postoperative chemotherapy. The aim of this study was to evaluate the rate of lymph node involvement and factors affecting it in clinically early-stage epithelial ovarian cancer (EOC; stages I, II). Patients and Methods: The study included 163 patients who underwent surgery at our hospital between January 2004 and April 2017 and who were diagnosed with early-stage EOC based on preoperative and intraoperative examination. Patient data were retrospectively analyzed. The rate of lymph node involvement and factors affecting it were analyzed. Results: Of 163 patients, 21 (12.9%) had lymph node metastasis, whereas 16 (16.3%) of 98 patients who underwent comprehensive lymphadenectomy had lymph node metastasis. According to the univariate results for patients undergoing any type of lymphadenectomy, the rate of positive lymph nodes was significantly higher (37.1%) in those with bilateral ovarian involvement (p < 0.001). The rate was significantly higher in patients with positive intraabdominal fluid cytology (25.9%; p < 0.001), serous histology (20.5%; p = 0.02), and grade 3 disease (33.3%; p < 0.001). In multivariate logistic regression analysis, the rate was significantly higher in patients with bilateral adnexal involvement (p = 0.012). The risk of positive lymph nodes was significantly higher in patients with grade 3 disease (p = 0.016). Conclusion: Comprehensive lymphadenectomy increases the detection rate for metastatic lymph nodes in patients with clinically early-stage EOC. The rate of lymph node involvement is significantly higher in grade 3 tumors, serous cytology, bilateral adnexal involvement, and positive intraabdominal fluid cytology.