Nine patients with chronic obstructive pulmonary disease were given oral aminophylline, intravenous aminophylline, and various inhaled and oral adrenergic bronchodilators to determine the effect of these agents on gastric acid secretion and gastrin release. Inhaled epinephrine hydrochloride resulted in an increase in basal acid output of borderline significance (.05 less than P less than .10). Oral aminophylline caused a significant increase in basal acid output from 2.43 to 4.06 mEq (P less than .05). Intravenous aminophylline also caused a significant increase in basal acid output from 0.66 to 2.19 mEq (P less than .01). There were no statistically significant changes in serum gastrin levels after administration of any of the bronchodilators. Aminophylline should be used with caution, if at all, in patients with peptic ulcer disease. In these patients, a beta agonist should be used for initial therapy. If the addition of aminophylline is necessary, antacids should be given.