A new gram-negative bacterium, Helicobacter pylori, has been found in gastric secretions. In view of an almost 9% incidence of unidentified gram-negative bacteria in aspiration pneumonia, the authors set out to prove that H pylori could be found in tracheal secretions. Eighteen sequential patients admitted to the intensive care unit who had endotracheal or nasogastric intubation for 24 hours or longer were studied. Of 20 sets of specimens from 18 patients. Helicobacter was recovered from 2(10%) of the endotracheal specimens. The authors conclude that H pylori can gain access to the endobronchial tree and therefore may contribute to the origin of pneumonia due to unidentified gram-negative bacteria.