Epstein-Barr virus (EBV) associated with lymphoid neoplasms demonstrates preferential association with certain viral strains. Previous subtyping studies have however been confined to analysis of sequence variability within a single locus in EBV. Variations have now been reported for several latently expressed EBV genes, including, EBNAs-1, 2 and LMP-1. Variant EBNA-1 strains have been identified in Burkitt's lymphomas and clustering of subtypes for LMP and EBNA-2 have been associated with either malignancy and/or clinical disease. To investigate the linkage between the variability in these three loci in EBV associated with lymphoid malignancies, we subclassified EBV-associated lymphoproliferations (9 reactive and 24 malignant) from HIV-negative and HIV-positive patients by analysis of the EBNA-1, LMP1, and EBNA-2 genes. Our results demonstrate that (1) EBV identical to the prototype B95.8 strain (Type 1 EBNA-2, wild type EBNA-1 and LMP-1) is very rarely associated with tumors. (2) The EBNA-1 variant V-leucine, restricted to malignant lymphomas in immunocompetent patients, was readily identified in non-malignant lesions in HIV infected patients. (3) Variations of EBNA-1 occur independent of variations at other loci.