Background Acute abdominal pain (AAP) is one of the most common causes of referral to an emergency department (ED), but information about its impact is limited. Objectives The objectives of this article are to define the prevalence of AAP among ED visits in a large university hospital and analyze its main clinical features. Methods All patients admitted at the Sant’Orsola, Malpighi University Hospital of Bologna ED on 12 a priori selected sample days in 2013 were included. General data were recorded for each patient. A total of 192 clinical variables were recorded for each patient with abdominal pain. Results During the observation period the ED assisted 2623 patients with a daily admission rate of 219 ± 20 (mean ± SD). Of these, 239 patients complained of AAP as their chief complaint at entry (prevalence = 9.1%). AAP prevalence was significantly higher in females than in males (10.4% vs. 7.8%; OR = 1.37; p = 0.021) as well as in foreign over Italian patients (13.2% vs. 8.5%; OR = 1.64; p = 0.007). The most frequent ED operative diagnoses were non-specific abdominal pain (n = 86, 36.0%) and gastrointestinal (GI) tract-related pain (n = 79, 33.1%; n = 19 upper GI, n = 60 lower GI). Conclusions AAP is a common cause of referral at EDs. Despite technological advances, non-specific abdominal pain is still the main operative diagnosis. Keywords: Acute, Abdominal, Pain, Management