We describe a 79-year-old man who had massive pleural effusion and a proliferation of prolymphocytic leukemia cells in the peripheral blood, bone marrow, and pleural effusion fluid. Immunophenotyping of leukemia cells revealed either CD3+CD4+CD8-CD25+ or CD3+CD4+CD8+CD25+. The antibody against human T-cell lymphotropic virus type I was negative. A diagnosis of T-PLL was made. The level of VEGF in the plasma or pleural effusion fluid was very high. Moreover, polymerase chain reaction analysis demonstrated an expression of VEGF mRNA in the leukemia cells, indicating a production of VEGF from leukemia cells and its involvement in the pathogenesis of T-PLL.