The influence of hepatic larval Taenia taeniaeformis infection on gastric acid secretory activity and gastric mucosal integrity was investigated. After 12 weeks of infection with 2,000 T. taeniaeformis eggs, the gastric pH values of control and infected rats were 4.1+/-0.6 (mean +/- SD) and 8.4+/-0.2, respectively. There was no difference in the basal acid secretion between control (1.7+/-0.7 micro Eq.H(+)/15 min) and infected (1.9+/-0.3) rats. However, infected rats failed to respond to histamine stimulation, the maximum acid output level being 2.8+/-0.4 in the infected rats, compared to 12.9+/-3.3 in control rats. Larval T. taeniaeformis infection resulted in the suppression of gastric acid secretion leading to hypergastrinemia.