Intestinal metaplasia is age related in Barrett's esophagus. The correlation among cellular characteristics of Barrett's esophagus, patient age, and malignant neoplasm is not well documented. This study, which describes a population of 66 patients with Barrett's esophagus spanning 1 to 80 years of age, analyzes the cellular constituents of their lesional tissues by endoscopic biopsy and histochemical and morphometric studies. Goblet cell metaplasia, identified in 50% (n = 14) of pediatric patients, increased significantly to involve 84% (n = 32) of biopsy specimens from adult patients with Barrett's esophagus. This increase was exponential by linear regression analysis (R2 = .64) between the ages of 5 and 29 years. Pediatric patients usually had 25 or less goblet cells per square millimeter of Barrett mucosa with no identifiable epithelial dysplasia or cancer; Nissen fundoplication lessened esophageal inflammation, but the Barrett mucosa persisted. Goblet cell metaplasia maintained a plateau (mean of 57 cells per square millimeter of Barrett mucosa) between the ages of 41 and 80 years. Dysplasia, in situ carcinoma, or invasive carcinoma was found in patients with Barrett's esophagus who were aged 41 years or older. This study demonstrates persistence of Barrett mucosa, increased incidence of goblet cell metaplasia, and predictable changes in goblet cell number with advancing patient age. The relationship between Barrett mucosa and malignant neoplasm remains uncertain, but the goblet cell may serve as a marker of disease chronicity in which setting neoplasia evolves. 