Recently, in situ hybridization (ISH) techniques have shown that Epstein-Barr virus (EBV) could be detected in tumor cells of most angiocentric T-cell non-Hodgkin's lymphomas (NHL). These studies included only a few cases of T-NHL of the lung and pulmonary B-NHL and have not been investigated. Furthermore, the expression of the EBV-encoded latent membrane protein (LMP), which is known for its oncogenic properties, has not been reported. Twelve pulmonary NHL (six angiocentric T-NHL and six B-NHL) arising in nonimmunocompromised patients were examined for the presence of EBV-EBER mRNAs and LMP with ISH and immunohistochemistry, respectively. Four cases of pulmonary lymphomas arising in immunocompromised patients were also included in the study for comparison (one T-NHL in a patient under immunosuppressive treatment and three B-NHL in AIDS patients). EBV-RNA and LMP were detected in tumor cells in two of six nonimmunocompromised angiocentric T-NHL and in the four immunocompromised NHL. The six nonimmunocompromised B-NHL were EBV negative. These results suggest that EBV is associated with some angiocentric pulmonary T-NHL arising in patients without overt immunodeficiency whereas it is absent in such patients with B-NHL. The presence of the transforming EBV-encoded LMP in tumor cells suggests that EBV may be involved in the pathogenesis of some pulmonary T-NHL.