From the longitudinal study of a cohort of HIV-positive patients, we report the case of a patient who initially harbored the Epstein-Barr virus (EBV) type 1 and subsequently developed an EBV-2-associated non-Hodgkin's B lymphoma a few years after an EBV-2 reactivation, or an exogenous reactivation, in the blood. At the time of diagnosis of hepatic lymphoma, the blood and the throat harbored high levels of the EBV-1 dominant strain. Sequence analysis of EBNA-2 gene revealed that: (1) type 2 EBV detected during reactivation and then in hepatic tumor was very likely to be the same strain and was mostly identical to the EBV prototype AG876; (2) type 1 virus conserved the same mutations during all the follow-up. These results suggest that EBV-2 might be associated with lymphomatogenesis and that a transient reactivation could lead to the development of an EBV-associated disease.