Abdominal pain is a common complaint for visits to ED. Among the causes of abdominal pain, the acute porphyria may confuse emergency physicians. With wide range of unspecific symptoms and signs, acute porphyria is rarely considered as a differential diagnosis of acute abdomen in ED. Some patients even receive unnecessary surgery. There are 32 patients who visited the ED of National Taiwan University Hospital because of acute porphyric attacks over the past 13 years. Ten patients (3 males and 7 females) were diagnosed with acute porphyria for the first time at ED. The onset of age ranged from 17 to 55 years (mean, 32 years). All of our patients presented with abdominal pain but without fever, dermatologic, and neurologic symptoms that are typically presented in acute porphyria. On the average, most of them repeatedly sought for medical help because of persistent symptoms for 4 times before being definitely diagnosed and thus receiving the optimal treatment. Meanwhile, all patients needed at least 2 kinds of analgesic, and most of them needed narcotic analgesia for pain control before diagnosis. The most commonest point of tenderness is over epigastrium (7 of 10 patients). The laboratory and image studies of our patients were of no diagnostic value for acute porphyria, except for Watson-Schwartz test. In summary, our study revealed that when a patient after puberty with repetitive visits because of severe abdominal pain without reasonable causes and needs narcotics for pain control, acute porphyria should be taken into consideration.