PURPOSE: Epstein-Barr virus(EBV) exists in the human population in two genetic forms, usually referred to as type 1 and type 2 which have been defined on the basis of sequence divergence in the EBNA-2 and EBNA-3 family genes. In this study, we were intended to investigate whether the subtypes of EBV in malignant lymphoma in Korea were associated with specific disease entities and geographical distribution. MATERIALS AND METHODS: Biopsy samples obtained from 18 Korean patients with malignant lymphoma including Hodgkin's disease(3 cases), B cell lymphoma(1 case), and NK/T cell lymphoma(14 cases) were analyzed to determine the subtype of EBV infected therein. DNA was extracted from formalin-fixed, paraffin-embeded tissues by ordinary method and specific viral sequences were sought using the polymerase chain reaction(PCR) and Southern blot hybridization assay. Oligonucleotide primers used for examination of EBV strain type were derived from the EBNA-3B and EBNA-3C coding regions. As a control, four cases of reactive hyperplasia were analyzed. RESULTS: The two of four reactive hyperplasia cases were associated with type 1 and the rest of two cases with both types. Among the 18 cases with malignant lymphoma, thirteen cases(72%) had type 1, one(6%) had type 2, and four(22%) had dual infections with both types. In case of NK/T cell lymphoma(14 cases) occupying 78% of 18 biopsy samples, 86%(12 cases) were associated with type 1, 7%(1 case) with type 2, and 7%(1 case) with both types. In case of Hodgkin's disease, all of three cases had both types. B cell lymphoma taking only one case of twenty two cases was determined as type 1. CONCLUSION: These observations indicated that type 1 EBV was predominant in Korean patients with malignant lymphoma, especially NK/T cell lymphoma and showed high frequency of dual viral infections(22%) in Hodgkin's disease as well as in reactive hyperplasia.