Background: In patients who were referred to the emergency department (ED) with abdominal pain, it is crucial to determine the presence of peritonism to allow for appropriate handling and subsequent referral to stationary departments. We aimed to assess the incidence of perceived peritonism in a contemporary ED and to make a comparable characterization on specified endpoints, including hospital stay, performed acute surgery, and ordered imaging. Methods: A single-center study was performed during 2010 in a contemporary Danish ED. We evaluated 1,270 patients consecutively admitted to the ED and focused on the patients with abdominal pain. Following a physical examination, the patients with abdominal pain were divided into those who had clinical signs of peritonism and those who did not. Results: Among the 1,270 patients admitted to the ED, 10% had abdominal pain. In addition, 41% of these patients were found to have signs indicative of peritonism, and 90% were admitted to the Department of Surgery (DS). Also, 24% of those patients with signs of peritonism and admission to the DS underwent surgical intervention in terms of laparotomy/laparoscopy. Five of the patients without peritonism underwent surgery. The patients perceived to have peritonism were younger at 34±3.0 years (mean ± standard error of the mean) than the patients who were not perceived to have peritonism, 52±2.8 years (P<0.05). They also had a shorter length of stay of 38.2±6.0 hours at the DS versus 95.3±18.2 hours (P<0.05). No differences with statistical significance were found regarding a stay in the emergency room (ER) or ordered imaging from the ER. Conclusion: Peritonism was a common finding in our setting. Peritonism did not require more acute surgery or imaging. The duration of the patient's stay in the ER was not influenced by a finding of peritonism. The evaluation of peritonism needs to be improved in the ED.