In this short review, we discuss primary diffuse large B-cell lymphoma of the testis, an entity that is most commonly seen in older patients. The most common clinical presentation is a unilateral testicular mass. Microscopically, the tumor shows diffuse infiltration of lymphocytes between intact seminiferous tubules. Spermatogenic arrest, interstitial fibrosis, and tubular hyalinization are commonly seen. The tumor is positive for B-cell markers by immunohistochemistry. Treatment has traditionally been with orchiectomy and combination chemotherapy; however, only a minority of patients enjoy a prolonged disease-free survival. Differential diagnosis includes seminoma and viral and granulomatous orchitis.