A systematic investigation of the histologic pattern of antral and corpus gastritis has been carried out in 1177 patients with various clinical conditions. An increased rate and severity of antral mucosa gastritis activity as well as surface epithelium cytotoxic lesions and Helicobacter pylori colonization, coupled with low rates and severity of the same parameters in corpus mucosa gastritis (usually of superficial nature so as to spare the integrity of acidopeptic glands) were the main features associated with active gastroduodenal peptic ulcer or antroduodenal mucosal erosions. Simultaneous antisecretory (omeprazole) and antibiotic treatment of duodenal ulcer patients led to the eradication of Helicobacter in 54 to 82% of patients when amoxycillin alone was used as antibiotic, and up to 94% of patients, when metronidazole was added to amoxycillin, as against none of patients treated with omeprazole alone, despite effective healing of their ulcer lesion. Very low (usually less than 5% per year) recurrency rates are reported in the literature for patients undergoing bacterial eradication, as against 50 to 80% in non-eradicated patients whose ulcer was healed by short term antisecretory drug treatment.