Late relapse of testicular tumor is rare. We report a case of recurrence of seminoma at left inguinal lymph node 18 years after initial treatment. A 63-year-old man had a left orchiectomy for left testicular tumor (T1N0M0) in February 1985, with no past history of scrotal or inguinal surgery. Histological examination revealed seminoma (pT1), and prophylactic radiotherapy (34.2 Gy) to para-aortic and left hemi-pelvic regions was perfomed. In November 2003, the patient presented with left inguinal swelling, and was referred to our hospital with suspicion of metastasis to left inguinal lymph nodes. Serum markers (AFP, hCG, hCGbeta and LDH) were normal. Computerized tomography (CT) showed three masses in the left inguinal region, but no other abnormal mass was detected at chest, abdomen or pelvis. Lymphoidectomy of the left inguinal region was perfomed in January 2004, and the mass revealed to be metastasis of seminoma by histological examination.