Evolutionary patterns of virus replication and distribution in lymphoid tissue during the early phases of HIV infection have not been delineated. Lymph node (LN) biopsies were excised from patients at different times after the estimated time of primary infection. Within 3 months of the acute viral syndrome, HIV was mostly present in individual virus-expressing cells in LNs; trapping of virions in the follicular dendritic cell (FDC) network was minimal or absent, but was the predominant form of HIV detected in LNs of subjects with chronic infection, either recent (4-20 months after primary infection) or long-term (>2-3 years after primary infection). Plasma viremia was significantly higher in patients during the first 3 months than in those recently infected; however, there were no significant differences in the number of virus-expressing cells per square millimeter of LN tissue in these two groups. Numbers of virus-expressing cells in lymphoid tissue were significantly lower in the subjects with long-term infection than in the other two groups. Therefore, during the transition from primary to chronic HIV infection, the level of HIV replication in lymphoid tissue remains elevated despite the fact that viremia is significantly downregulated. These findings have implications for therapeutic strategies in primary HIV infection and in recent seroconvertors.