The clinical significance of Dientamoeba fragilis infection is controversial. We describe a case-history of a 16-year-old patient, who had suffered severe abdominal discomfort and flatulence through his lifetime. He was eventually diagnosed with D. fragilis infection, and eradication of D. fragilis with high-dose metronidazole kept him without symptoms for one year. Recurrence of the symptoms and recurrence of the D. fragilis infection was thereafter treated successfully with paromomycin.