Abstract Interleukin 2 (IL 2) is known to have multiple immunoenhancing activities that are related to its ability to promote the proliferation and the expression of effector functions of human T lymphocytes. We investigated the potential of IL 2 to induce human T lymphocyte migration. Unstimulated T cells did not respond to IL 2, but T cells exposed to dextran or phytohemagglutinin did respond to IL 2 concentrations from 0.01 to 10.0 U/ml, with significantly increased migration. This activity could be specifically blocked with anti-Tac antibody. Analysis of T lymphocyte subsets revealed that OKT4+ but not OKT8+ lymphocytes responded to IL 2 in the chemotaxis assay. Checkerboard analysis demonstrated that the IL 2-induced chemoattractant activity was predominantly chemotactic rather than chemokinetic in nature. The activity of IL 2 was compared with that of another chemoattractant lymphokine, lymphocyte chemoattractant factor, which was found to stimulate lymphocyte migration without prior exposure to mitogen, and which was not inhibited by anti-Tac. Our data suggest that the lymphocyte migratory response to IL 2 is under the control of the inducible receptor recognized by anti-Tac in a manner similar to the proliferative response to IL 2, but differs from proliferation in its OKT4+ cell specificity.