Campylobacter enteritis has emerged as one of the commonest forms of human diarrheal illness. Acute enteritis is the most common presentation of Campylobacter jejuni infection, but symptoms and signs are not so distinctive that the physician can differentiate it from illness caused by other organisms. Several selective media, with and without blood, have been developed for the isolation of these organisms from stool specimens. These isolation procedures allow growth of most of the C. jejuni and Campylobacter coli, but are too inhibitory for the isolation of several other Campylobacter species such as C. jejuni subsp doylei, Campylobacter upsaliensis, Campylobacter concisus, Campylobacter curvus, Campylobacter hyointestinalis, Campylobacter fetus, and “Campylobacter butzleri”. These Campylobacter strains can only be isolated successfully by means of a filtration technique. Helicobacter pylori is now recognized as the major causative agent of chronic type B gastritis, both in adults and in children. The importance of H. pylori in peptic ulcer disease, especially duodenal ulcer, is becoming widely accepted, and pathogenic hypotheses for the development of duodenal ulcer from antral gastritis have been developed. The exact mode of transmission of H. pylori remains unknown, although interhuman transmission of this organism through oral-oral or oral-fecal routes has been suggested. The search for optimal therapy is still continuing.