The effects of coffee on exocrine pancreatic secretion are unknown but may be important, because a link between chronic stimulation of pancreatic secretion and experimental chemical carcinogenesis and an association between coffee drinking and human pancreatic adenocarcinoma have been reported. We measured exocrine pancreatic trypsin and gastric acid secretions collected through orogastroduodenal tubes and serum gastrin in eight non-coffee drinkers and eight coffee drinkers. During fasting, after one interdigestive cycle control period, one of four 250-ml samples [plain water, water plus caffeine (4.6 mg/kg), decaffeinated coffee (127.9 mg/kg), caffeinated coffee (127.9 mg/kg)] was administered through the orogastric tube. Caffeinated and decaffeinated coffee (p = 0.008), caffeine (p = 0.03), and an unidentified substance(s) in coffee other than caffeine (p = 0.008) were associated with increased interdigestive exocrine pancreatic trypsin secretion. In addition, we also confirmed that coffee and caffeine stimulated gastric acid secretion (p = 0.02) and decaffeinated coffee raised serum gastrin concentrations (p = 0.005). If an association between coffee and pancreatic carcinogenesis exists, chronic stimulation of the exocrine pancreas by secretagogues could result in a gland susceptible to carcinogenesis.