The small colonic mucosal nodules that have been referred to in the past as lymphatic nodular hyperplasia are felt to represent a normal response of the prominent colonic lymphatic tissue in children. To support this hypothesis, a prospective study of all air-contrast barium enemas, colonoscopies, and intestinal biopsies performed during 1 yr was carried out. During that year 48 patients had air-contrast barium enemas, and 21 of these 48 patients also had colonoscopy and mucosal biopsies. Greater than half of the children studied by air-contrast barium enema (26 out of 48) and colonoscopy (12 out of 21) had nodular colonic mucosa. These nodules were described at colonoscopy as being smooth surfaced, yellowish-white, 1-2 mm in diameter. There was no correlation between the presence or absence of these nodules with any symptom or symptom complex. The younger patients, the more frequently these nodules were oberved. No immunologic disorder was associated with the nodular colonic mucosa in the children that were tested. Nodular colonic mucosa in childhood should be considered a frequent finding indicative of normal lymphatic response to nonspecific stimuli, which may often be infectious in nature.