Chronic gastritis is frequently accompanied by Helicobacter pylori infection and associated with a reduced gastric blood flow. To investigate the possible relationship between the two phenomena, 20 outpatients with histological antral gastritis with or without concomitant duodenal ulcer, 10 of them Hp positive and 10 negative, were selected and compared with a matched group of ten healthy controls. Mucosal blood flow was measured in the gastric antrum by laser Doppler flowmetry during endoscopy. In both groups of patients with chronic gastritis the values were significantly lower than normal (p < 0.01), the difference between Hp+ and Hp- cases being statistically not significant. In six of the Hp+ patients, eradication therapy with omeprazole+amoxycillin was carried out because of concomitant duodenal ulcer. At 6 weeks eradication was successful in four patients, but perfusion values remained unchanged. Mucosal blood flow in chronic gastritis is reduced regardless of concomitant H. pylori infection and eradication has no influence on gastric perfusion. Therefore H. pylori appears to have no direct effects on gastric microcirculation.