Varicocele caused by diffuse large B-cell lymphoma is rare. Here, we reported our findings in a 48-year-old man, who was admitted to our hospital because of left varicocele for 5 months. The operation of high ligation of the left spermatic vein was performed. However, we found a 6.0 cm×3.0 cm×3.0 cm solid mass in the region of the inside of the left iliac vessels. The lump was removed and the histopathologic diagnosis was diffuse malignant large B-cell lymphoma. The patient was started on a CHOP (cyclophosphamide, adriamycin, vincristine, and prednisolone) definitive therapy. Here, we reported our findings in a 48-year-old man, who was admitted to our hospital for the left varicocele for 5 months. The operation of high ligation of the left spermatic The vein was performed. However, we found a 6.0 cm × 3.0 cm × 3.0 cm solid mass in the region of the inside of the left iliac vessels. The lump was removed and the histopathologic diagnosis was diffuse malignant large B-cell lymphoma. The patient was started on a CHOP (cyclophosphamide, adriamycin, vincristine, and prednisolone) definitive therapy.