The leukocyte migration inhibition test was performed in 39 patients with Helicobacter pylori infection and in 38 patients without such infection. The culture of Helicobacter pylori was used as antigen. A highly significant inhibitory effect on leukocyte migration was found in patients with Helicobacter pylori infection. The results can be taken as proof of a systemic immune response to helicobacters at the cellular level in patients with Helicobacter pylori infection.