Decreased blood cell--e.g. lymphocyte--motility is seen in a number of vascular and autoimmune diseases. Pentoxifylline (Pf) shows a well-known therapeutic effect in several vascular alterations by causing the redistribution of blood cell cytoskeleton and increased microcirculation. As most literary data on Pf concern red blood cells and granulocytes authors here investigated the effect of Pf on previously decreased lymphocyte migration and chemotaxis. Results of in vitro studies suggest that Pf enhances impaired lymphocyte motility in obliterative arteriosclerosis and systemic lupus erythematosus and thus may also be introduced in the treatment of polysystemic autoimmune diseases.