Lymphocytic gastritis and lymphocytic colitis are two rare disorders of unknown etiology, only diagnosable by histology. Simultaneous occurrence of lymphocytic colitis and lymphocytic gastritis has not been described up to now. A 69-year-old female patient was examined because of crampy abdominal pain and watery diarrhea. Laboratory tests did not reveal an etiology and in colonoscopy the colon and terminal ileum were normal. Histology disclosed lymphocytic colitis. Esophagogastroduodenoscopy showed erosive bulbitis. Biopsies of the stomach revealed lymphocytic gastritis. A second colonoscopy one year later showed the development of collagenous colitis.