A 32-year-old female was admitted to our hospital because of abdominal fullness, jaundice and pretibial edema in November, 1987. Leukocyte count of peripheral blood showed 13300/microliters with 84% leukemic cells and bone marrow was normocellular with 63.6% leukemic cells. Leukemic cells had azurophilic large granules with basophilic cytoplasm and positive for CD 2, OKIa 1, NKH-1 and negative for CD 3, CD 4, CD 8, CD 16. T cell receptor (TCR) genes for beta, gamma and delta chain and immunoglobulin heavy chain gene were in germ line configuration. These cells also had natural killer (NK) activity and antibody dependent cell mediated cytotoxicity (ADCC) activity. These observations suggested that they were derived from NK cell lineage. It is often difficult to demonstrate their clonalities in lymphoproliferative disorder of granular lymphocytes (LDGL). In the present case, the analysis of EBV genome using termini probe demonstrated polyclonal bands, while we found constant chromosome abnormalities; 47 XX, +3. From these observations, this case was considered to have several clones, and one of which could be detected by chromosome analysis. The analysis of EBV genome using termini probe may be useful to demonstrate their clonalities in LDGL in addition to conventional chromosome analysis.