Background: Although lymphadenectomy is advised for accurate surgical endometrial-carcinoma staging, the procedure is not performed regularly worldwide. Most studies on it include few patients and mainly compare pelvic with pelvic/para-aortic lymphadenectomy. Comparing lymphadenectomy with non-lymphadenectomy is rare. The current study examined prognostic significance and survival advantages of pelvic and pelvic/para-aortic lymphadenectomy compared to no lymphadenectomy. Materials and Methods: This was a retrospective cohort analysis of 75 patients with endometrial carcinomas. The patients were divided into 3 treatment groups based on whether or not lymph-node dissection was performed and the extent of the dissections: (1) pelvic lymphadenectomy; (2) pelvic/para-aortic lymphadenectomy; and (3) no lymphadenectomy. Correlations were analyzed among the surgical techniques used for the 3 groups with respect to the need for adjuvant radiotherapy or chemotherapy, recurrences, and survival outcomes. Results: Pelvic and pelvic/para-aortic lymphadenectomy produced more-favorable overall survival (OS) and progression-free survival (PFS) rates than no lymphadenectomy (p = 0.047). A significant difference was noted among the 3 treatment groups for OS rate and disease-free survival rates (p = 0.015 and 0.017, respectively). The recurrence rates were 47.1%, 35.7%, and 68.8% in the pelvic lymphadenectomy, and pelvic/para-aortic lymphadenectomy, and no lymphadenectomy groups, respectively (p = 0.037). Conclusions: This study showed that pelvic and para-aortic lymphadenectomy improved the OS and PFS rates of patients with endometrial cancer.