Lymphomatoid granulomatosis is currently classified as part of a spectrum of angiocentric immunoproliferative lesions. These were initially thought to be of T-cell phenotype, but recent papers have shown that some cases are B-cell proliferations, sometimes associated with Epstein-Barr virus infection. We reviewed the clinicopathological features of 16 patients with pulmonary lymphomatoid granulomatosis, using immunohistochemistry to assess the phenotype of the infiltrate, the polymerase chain reaction to look for immunoglobulin heavy chain and T-cell receptor gene rearrangements, and in-situ-hybridization to look for Epstein-Barr virus infection. In seven of seven cases the atypical lymphoid population was of B-cell phenotype, with four cases showing evidence of either monoclonality or oligoclonality. All seven cases, including those that lacked unequivocal proof of malignancy, behaved aggressively. Epstein-Barr virus RNA was detected in four cases. We conclude that some cases of lymphomatoid granulomatosis are B-cell lymphomas, sometimes associated with Epstein-Barr virus infection.