BACKGROUND: Synchronous isolated external iliac lymph node metastasis of ascending colon cancer is extremely rare, and its treatment strategy has not been established. In this report, we present a case of long-term survival after surgical resection and adjuvant chemotherapy for ascending colon cancer with synchronous isolated right external iliac lymph node metastasis. CLINICAL CASE: A 65-year-old woman with anorexia and anemia was referred to our hospital. Colonoscopy and computed tomography revealed a three-quarter circumferential type 2 tumor from the cecum to the ascending colon, along with regional and right external iliac lymph node swelling. We diagnosed ascending colon cancer with right external iliac artery lymph node metastasis. An open right hemicolectomy with D3 and right external iliac lymph node dissections were performed. Results of histopathological examination showed that both lymph nodes were metastasized from ascending colon cancer. The patient received eight courses of capecitabine and oxaliplatin therapy as adjuvant chemotherapy. At 60 months after surgery, the woman has not had a recurrence. CONCLUSIONS: Surgical resection and adjuvant chemotherapy may be an effective treatment strategy for synchronous isolated right external iliac lymph node metastases from ascending colon cancer.