Chronic abdominal pain, constipation, diarrhea, and anorexia are often difficult symptoms for a pediatrician to evaluate. These children are often thought to have psychosomatic complaints. It has been noted that stools for ova and parasites obtained on some of these children have demonstrated parasites often thought to be nonpathogenic. Thus, a retrospective evaluation was performed of children seen at UCLA during the time period from June 1976 through November 1977 in whom the parasite Dientamoeba fragilis (DF) was isolated from stool specimens. DF was present in 14% of 350 children who had stools analyzed for ova and parasites. DF was the only parasite obtained in 9% of the 350 children. History was available from 28 of these 37 patients in whom DF was the only pathogen. Children were aged 10 months to 17 years; males predominated 1.6 to 1. Forty-eight percent of children had been born in the U.S. and had no history to foreign travel; 39% were from Mexico or South America. Ninety-three percent (26/28) had gastrointestinal symptomatology (abdominal pain, diarrhea, anorexia or constipation); 2 (7%) were asymptomatic. The most common symptom in these children was diarrhea (57%) which was often intermittent. Abdominal pain, often vague and localized to the lower abdominal quadrants was present in 54%; anorexia and fever were present in 39% and 29% respectively. Children were treated with either diiodyhydroxyquin, metronidazole or tetracycline and all but one were asymptomatic on followup evaluation.