Primary lung lymphoma (PLL) and diffuse large B-cell lymphoma (DLBCL) is a rare entity and the biological features, clinical presentation, prognosis markers and treatment have not been well defined. We present 82 cases of PLL-DLBCL in a uniform population and treated with conventional chemotherapy: CHOP (cyclophosphamide, doxorubicin vincristine and prednisone). To the best of our knowledge, this is the largest series with long term follow reported. We also performed immunohistochemical studies to determine if the cell of origin [germinal center (GC) and non-GC] have a prognostic significance. All patients were at an early stage and low-clinical risk without bulk disease and normal levels of lactic dehydrogenase and beta 2 microglobulin. Complete response was achieved in 77 cases (94%), actuarial curves at 10 years showed that event-free survival (EFS) was 90% and overall survival was 92%. Fifty-nine patients were of GC phenotype and 23 of non-GC phenotype. Complete response (93% versus 91%), EFS (91% versus 80%) and overall survival (89% versus 78%) respectively, were not statistically different. Treatment was well tolerated, and second late events have not been seen. We conclude that PLL-DLBCL is an extranodal lymphoma with a good prognosis event in patients of non-GC phenotype.