A nameless spirillar organism in search of a disease only a few years ago, Helicobacter pylori has seen its fortunes suddenly reversed. After a rapid succession of name changes and some acrimonious disputes across continents, in less than a decade H. pylori has been catapulted to the centre stage of gastroenterological and microbiological research and has topped the most-wanted list of the pharmaceutical industry. The discovery of H. pylori has provided the momentum for the formation of the group that eventually created the Sydney System. Today, H. pylori is increasingly recognized as one of the most prevalent human pathogens worldwide. Its causal association with chronic active gastritis is undisputed and its role in the pathogenesis of peptide ulcer disease, although still poorly understood, is universally accepted. Furthermore, possible connections between chronic H. pylori infection and gastric carcinoma and primary gastric lymphoma are now being explored with increasing alacrity. With a few notable exceptions, pathologists have remained passive spectators of these exciting discoveries and have allowed gastroenterologists and microbiologists to set the pace in the quest for the determinants of gastritis, peptic ulcer and gastric cancer. This article is intended to outline some of the accepted facts on the development, progression, and pathology of H. pylori gastritis and to pose questions about this elusive infection. The authors hope that it might also contribute to stimulate further research, particularly on those aspects that are eminently suited to be addressed by pathologists.