The present study was undertaken to assess the locomotor capacity of lymphocytes from patients with human immunodeficiency virus (HIV) infection by a polarization assay. In addition, the capping phenomenon of lymphocytes from HIV-infected patients or in vitro preincubation of lymphocytes with HIV-envelope glycoproteins, gp41 and gp120 was evaluated. A significant decrease in polarized lymphocytes from patients with acquired immunodeficiency syndrome (AIDS) was observed. On the other hand, the capping phenomenon either of lymphocytes from AIDS patients or of lymphocytes from healthy donors preincubated with gp41 and gp120 was reduced but not significantly.