It is thought that Helicobacter pylori colonization of the gastric mucosa might stimulate the production of several cytokines, which might trigger and maintain the gastric inflammation associated with Helicobacter pylori infection. In the present study we evaluated interleukin-1 beta. interleukin-6, and the soluble receptor of interleukin-2 both in mucosal homogenates and in the sera of Helicobacter pylori-infected (39 cases) and uninfected (40 cases) patients to investigate whether there was any relationship between variations in cytokines and (1) the severity of Helicobacter pylori-associated gastritis or (2) CagA-positive Helicobacter pylori strains. Mucosal, but not serum levels of interleukins-1 and -6 and interleukin-2 receptor were significantly higher in infected than uninfected patients. Serum levels of Helicobacter pylori antibodies were significantly higher in infected than uninfected patients. These levels correlated with mucosal interleukin-1 beta. The degree of antral or body inflammatory grade was higher in infected than in uninfected patients; cytokines levels were higher in patients with high-grade gastritis, most of whom were Helicobacter pylori positive. Patients infected with CagA-positive strains also had higher levels of interleukin-1 beta, but not of interleukin-2 receptor or interleukin-6. In conclusion. Helicobacter pylori infection results in a local increase in interleukins-1 beta and -6 and interleukin-2 receptor associated with high-grade mucosal inflammation. Interleukin-1 beta seems to favor anti-Helicobacter pylori antibody production, and mucosal levels are enhanced mainly in patients infected with cytotoxic Helicobacter pylori strains.