Background:Serum CA 125 is elevated in many physiological and pathological conditions that are related to endometrial proliferation as menstrual cycle, pregnancy, endometriosis, and endometrial carcinoma. Many researchers studied Serum CA 125 level and its role in the assessment of endometrial cancer patients. The relation between the CA 125 level and many variables was demonstrated, such as lymph node involvement, myometrial invasion, disease stage, and overall survival. Aim: to evaluate the relation between the tumor marker CA 125 and lymph node metastasis. Patients and Methods: A total number of twenty-six patients with endometrial carcinoma were enrolled in the study. Serum CA 125 was withdrawn preoperatively to all patients. The patients were subjected to total abdominal hysterectomy and bilateral salpingo-oophorectomy. A method of lymphatic mapping using patent blue dye was performed. The sentinel lymph node(s) and non-sentinel lymph nodes were sent for H&E staining. Results: On evaluating serum CA-125 of ≤35 IU/mL in predicting the absence of lymph node involvement as confirmed pathologically, the sensitivity was 87%, specificity 100%, positive predictive value 100%, negative predictive value 50% with accuracy 88.5%. Conclusion:CA 125 is a valid method in the preoperative assessment of patients with endometrial carcinoma.