Purpose: To estimate the cost of the diagnosis and management of nontraumatic abdominal pain (NTAP) in the emergency room (ER) and to determine the factors that affect the cost of diagnosis and management of this type of pain. Materials and Methods: In total 345 patients with NTAP and complying with the study criteria were included. After they discharged from the ER, the expenses of diagnosis and treatment of the patients were calculated. The expense results were compared to each other especially in terms of age, sex, and underlying disease. Results: In the study group, 60% of patients were female. The mean age of the patients was 36.5 (range: 17-92). The overall mean time of the patients with NTAP spent in the ER was 4.92 h (range: 1-151 h). The mean expense amount of the patients with NTAP in ER was 112.2 TL (range: 14-1394 TL). Being above the age of 60, having accompanying symptoms, having surgical abdominal pain, having pathological findings in abdominal examinations, and being referred from other centers or being referred back to the ER with the same complaint were the most important factors that determined the follow-up period and expenses of NTAP patients in the ER. Conclusion: Such information describing the cost of diagnosis and management of NTAP should be taken into account to determine cost effective strategies and to establish reference guidelines.