In order to evaluate the relationship between the patient-identified regions of abdominal pain and the disease diagnosis, a prospective study was conducted at General Medicine Outpatient Clinic, Saga Medical School Hospital. Four hundred eighty-nine outpatients complaining of abdominal pain at the first visit were classified into 10 groups according to the pain region complained of, i.e., whole abdominal, epigastric, right subcostal, left subcostal, right flank, left flank, periumbilical, right-lower, mid-lower, and left-lower; the clinic physicians and authors in joint-participation assigned the groups through studying the medical records. Comparisons were made in order to calculate sensitivity, specificity, and the positive and negative likelihood ratios between the pain regions and disease diagnoses. In general, the sensitivity of history-taking and physical examination is low, but specificity is high in relation to epigastric pain and gastroduodenal diseases, right subcostal pain and hepatobiliary diseases, and mid lower pain and gynecological diseases (above 0.5). Comparative analysis between the pain regions complained of by the patient in the initial clinic visit and the medical diagnoses yielded clinically useful information as to the efficacy of medical history-taking and physical examination in the identification of abdominal diseases. J Epidemiol, 1997 ; 7 : 27-32.