Follicular lymphoma (FL) is a low-grade lymphoma, with rare presentation of leukemic phase in peripheral blood at the diagnosis. We describe a 49-yr-old woman who developed leukemic phase of FL in a 3 mo period after histological diagnosis of peripheral lymph node. To confirm the final diagnosis, flow cytometry (FCM) of peripheral blood, nested PCR with bcl-2 rearrangement, and cytogenetic analysis of peripheral blood and bone marrow cells were done. Lymphoma cells were negative for CD38 and expressed monoclonal surface immunoglobulins with relatively strong and "bright" IgD and "dim" kappa-chain by FCM analysis. Although the patient presented with generalized lymphadenopathy, massive peripheral blood and bone marrow involvement, she achieved complete clinical response after first-line chemotherapy COP and rituximab. She is still in a good condition with follow up over 2 yr.