The discovery of Helicobacter pylori was made by Barry Marshall at the Royal Perth Hospital in Western Australia in collaboration with Robin Warren. Warren, a histopathologist, was investigating a bacterium which he had observed on gastric biopsies in 1979.H. pylori associated gastritis is today recognized as the major cause of duodenal and gastric ulcers, gastric adenocarcinoma and mucosa-associated lymphoid tissue lymphoma. This organism did not resemble any known species, either in morphology or biochemistry. It was cultured using isolation techniques for Campylobacter. Thus, initially it was named Campylobacter pyloridis. The name was grammatically corrected to Campylobacter pylori. Helicobacter pylori-associated gastritis is today recognized as the major cause of duodenal and gastric ulcers, gastric adenocarcinoma and mucosa-associated lymphoid tissue lymphoma.