Adenocarcinoma of the rectum and anal canal with inguinal lymph node metastasis(ILNM)is rare and the prognosis is generally poor. The aim of this study was to clarify the clinical significance of selective inguinal lymph node dissection and total mesorectal excision after preoperative therapy for adenocarcinoma of the rectum and anorectal canal with clinically suspected ILNM. Of the 15 patients, 11 received preoperative chemoradiotherapy, 3 received chemotherapy, and 1 received chemotherapy after chemoradiotherapy. 14 patients received preoperative therapy followed by FDG-PET scans were performed in 14 patients after preoperative treatment. 5 patients had negative FDG accumulation in inguinal lymph nodes on FDG-PET scans, and postoperative pathological diagnosis was also negative for metastasis in the inguinal lymph nodes. Of the 9 patients with positive FDG accumulation, 4 had pathologically positive inguinal lymph nodes, 7 had postoperative inguinal seroma, the 5-year survival rate was 77.5%, and the 5-year recurrence-free survival rate was 64.2%. No patient had a recurrence in the inguinal region. Patients with adenocarcinoma of the rectum and anal canal with clinical ILNM had good long-term survival after radical resection with preoperative therapy.