Smokers show higher rates of peptic ulcer disease (PUD) than nonsmokers, probably due to detrimental effects on the gastric mucosa. Surface-active phospholipids (SPL) are believed to play a key part in gastric cytoprotection. The aim of this study was to determine the chronic effects of smoking on the gastric SPL and to relate them to H. pylori (Hp) -induced effects. Gastric juice was aspirated in 52 patients, with normal findings at planned upper gastrointestinal endoscopy, and concentrations of seven phospholipid subclasses were analyzed. Concentrations of lysophosphatidylethanolamine (1-PE) were increased (P = 0.006) in smokers compared to nonsmokers in non-Hp-infected samples. Nonsmokers infected with Hp showed increased levels of 1-PE (P = 0.01) and phosphatidylinositol (PI) (P = 0.02) compared to subjects not infected. In human gastric juice PI seems to be the dominating PL subclass, in contrast to the composition in biopsy specimens. We also found both Hp-infected and smoking subjects to have higher concentrations of more polar phospholipid subclasses, ie, 1-PE, making the mucosa more vulnerable to acid attack as the gastric surfactant becomes less hydrophobic.