Morphological, immunologic, and functional properties of peripheral blood cells from two patients with chronic proliferations of granular lymphocytes are described. Cells from both patients showed a heterogeneous pattern from both a morphological and immunologic standpoint, indicating a polyclonal, rather than a monoclonal, expansion of these cells. In fact, both large and small-to-medium-sized granular lymphocytes were observed, and different percentages of positivity were found in the analysis with a large panel of monoclonal antibodies. Serologic and histologic features support the hypothesis that this lymphocytosis could be secondary to bacterial or viral infections rather than a primary event, suggesting that these patients may have chronic reactive immunoregulatory disorders.