The morphology of the gastric cardia in children and the significance of inflammation in this region are unknown. Some investigators propose that the cardia is comprised of mucous glands at birth, whereas others suggest that mucous glands, when present, represent a metaplastic response to gastroesophageal reflux disease. The aim of this study was to evaluate the morphologic features of the cardia in a pediatric population and to determine the significance of inflammation in this region by correlating the pathologic features with clinical and endoscopic data. Routinely processed hematoxylin and eosin-stained mucosal biopsies of the cardia from 74 pediatric patients (age range 0.1-18 years; male/female ratio 0.76:1) without endoscopic evidence of Barrett's esophagus were examined for a variety of histologic features, such as the type of glandular epithelium (mucous, mixed mucous/oxyntic, oxyntic), and the amount and type of inflammation both within 1.0 mm and >1.0 mm from the squamocolumnar junction. The results were correlated with the patients' clinical symptoms and with other histologic features, such as esophagitis, gastritis, Helicobacter pylori, and the presence of goblet cells. Our results show that either pure mucous glands (81%) or mixed mucous/oxyntic-type glands (19%) were present within 1 mm of the squamocolumnar junction in all of the patients (100%) in this study. Patients with mixed mucous/oxyntic glands located <1 mm from the squamocolumnar junction were more likely to have goblet cells than were patients with mucous glands alone, but they did not differ with respect to any other feature, including patient age. However, both active esophagitis and increased inflammation in the cardia correlated positively with a longer length of pure mucous glands in the gastroesophageal junction region. Of the cases with inflammation (carditis), eosinophils correlated with the presence of active esophagitis (a histologic manifestation of gastroesophageal reflux disease), whereas increased lymphocytes correlated with chronic H. pylori gastritis. In summary, a small amount of pure mucous-type glands is present in the cardia in most pediatric patients, a finding that supports a congenital origin for this type of epithelium. However, our finding of an association between length of mucosa occupied by pure mucous glands and active esophagitis suggests that injury and repair related to gastroesophageal reflux disease may contribute to expansion of the zone occupied by cardia-type mucous glands.