Lymphocytes play a central regulatory role in mechanisms contributing to impaired function of immune system in atopy. The aim of our study was evaluate the mitogen-induced proliferation of lymphocytes in a group of asymptomatic, seasonal allergic rhinitis patients. A highly significant lower mitogen-induced proliferation and, in contrast to other studies, significantly lower background proliferative activity of lymphocytes were found in the atopic persons, comparing to the controls. We concluded that the decreased mitogen-induced proliferation of lymphocytes observed in allergic patients reflects abnormal T cell function, which is due to the atopic status, and not only as it was believed to the antigen-induced lymphocyte activation.