Aim: Lymphocyst is one of the most common complications of lymphadenectomy and generally encountered during uro-gynecological oncology surgeries. We aimed to define the risk factors for formation of a lymphocyst in patients with various gynecological cancer types in whom a lymphadenectomy was performed. Methods: This retrospective study was performed on 206 patients. Of the 206 patients, 100 were diagnosed with a lymphocyst, and 106 were assigned to a control group. Laboratory findings and surgical characteristics of the patients were compared. Results: No differences were observed in age, pre-operative hemoglobin; platelet, white blood cell, and lymphocyte counts; or pre-operative albumin level (p=0.315, 0.500, 0.525, 0.683, 0.740, and 0.97, respectively). A significant effect of the heparin dose x heparin days interaction and lymphocyst formation was observed (p=0.002). Lymphocysts were most frequently detected in the ovarian cancer subgroup (49%). Significant differences were detected between the groups in the percentages of patients who underwent CT only and RT only treatments (p=0.001 and 0.002, respectively). The logistic regression analysis revealed a relationship between the LMWH dose x days interaction and formation of a lymphocyst (OR, 1.10; 95% CI, 1.0-1.13; p=0.01). Conclusion: The association between total LMWH dose administered and the formation of lymphocysts in patients with gynecological pelvic cancer was investigated for the first time. Significant relationship between heparin dose x days and lymphocyst formation was found. Although anticoagulation with LMWH is essential for preventing thromboembolism, it should be used appropriately to prevent other complications, such as bleeding and lymphocysts.