A 20-year-old African female was hospitalized several times for diffuse chronic abdominal pain. The following exclusions were made: Acute adnexitis (by laparoscopy), acute appendicitis (by appendectomy), gastric ulcerations (by esophagogastroduodenoscopy) as well as Crohn's disease and ulcerative colitis. However, once taking a closer microscopical look at the mucosa, that otherwise appeared colonoscopically to be normal, multiple eggs of schistosomiasis mansoni (S. mansoni) were found in the colon as well as the rectum. Thus, the diagnosis of an intestinal bilharziosis was finely established. In retrospect even the sample taken for the appendix could have indicated this diagnosis already earlier on. Both the antibodies (ELISA/IFAT) and the specific immunoglobulins (IgE) for S. mansoni proved significantly positive. Therapy of choice was a single oral dosage of praziquantel. Migration and tourism have considerably increased the range of tropical and infectious diseases that need to be included into differential diagnosis. This case report focuses on intestinal bilharziosis as a potential underlying cause of chronic abdominal pain in immigrants of endemically affected areas. Direct diagnosis is the most important diagnostic method. The adult worms are usually inaccessible, so the method of choice to assess both diagnosis and the degree of activity of a chronic infection is evidence of living eggs in the stool. Alternatively, in case of lack of direct evidence diagnosis can be established by endoscopy and rectal biopsy.