OBJECTIVE: Endometrium cancer (EC) is the most prevalent cancer affecting women in developed countries. There is debate about the need to perform lymphadenectomy in cases with a tumor diameter >2 cm. The aim of our study is to research the prediction of lymph node metastasis using tumor size in stage 1A endometrioid endometrium cancer (EEC). PATIENTS AND METHODS: The study enrolled cases operated in the clinic due to stage 1A EEC (FIGO 2009) from December 2010-2021. The correlations of age, age interval, parity, type of operation, tumor diameter, myometrial invasion, histological grade, and lymph node metastasis were statistically analyzed. The cut-off point for tumor size was determined with the ROC curve and Youden index. RESULTS: The study analyzed a total of 292 cases, and the mean age of cases was 62.3±10.0 years. Of the cases, 79.5% had histological grade 1, and 20.5% had grade 2. Myometrial invasion ≤50% was detected in 69.5%, and no myometrial invasion was detected in 30.5%. The mean tumor diameter was 34.0±18.0. Lymph node metastasis was identified in 6 cases (2.1%). Based on the tumor diameter cut-off value of 35 mm, sensitivity was 100%, and specificity was 50.3%. 116 cases with tumor diameter >35 mm and 176 with diameter ≤35 mm, and grade 2 histology and lymph node positivity were found statistically significant between these groups (respectively, p=0.012 and p=0.038). The lymph node metastasis risk was 0% in cases with tumor diameter ≤35 mm, while it was 5.2% in cases with tumor diameter >35 mm. CONCLUSIONS: The general approach in stage 1A EEC is not to perform lymphadenectomy. However, when the tumor diameter is noted, lymphadenectomy may be considered as the lymph node metastasis risk increases in cases with a tumor diameter of 35 mm or more. There is a need for more clinical studies on this topic.