Primary testicular non-Hodgkin lymphoma (PTL) comprises around 9% of testicular cancers and 1-2% of all non-Hodgkin lymphomas. Its incidence is increasing and it primarily affects older men, with a median age at presentation of around 67 years. By far the most common histological subtype is diffuse large B-cell lymphoma, accounting for 80-90% of PTLs. Most patients present with a unilateral testicular mass or swelling. Up to 90% of patients have stage I or II disease at diagnosis (60 and 30%, respectively) and bilateral testicular involvement is seen in around 35% of patients. PTL demonstrates a continuous pattern of relapse and propensity for extra-nodal sites such as the central nervous system and contralateral testis. Retrospective data have emphasised the importance of prophylactic radiotherapy in reducing recurrence rates within the contralateral testis. Recent outcome data from the prospective IELSG-10 trial have shown far better progression-free and overall survival than historical outcomes. This supports the use of orchidectomy followed by Rituximab- cyclophosphamide, doxorubicin, vincristine and prednisolone (R-CHOP), central nervous system prophylaxis and prophylactic radiotherapy to the contralateral testis with or without nodal radiotherapy in patients with limited disease. Central nervous system relapse remains a significant issue and future research should focus on identifying the best strategy to reduce its occurrence. Here we discuss the evidence supporting combination chemotherapy and radiotherapy in PTL.