A retrospective study on 450 patients admitted in emergency with acute abdominal pain in a general surgical unit of the Ist Institute of Surgery of the University of Rome "La Sapienza" was carried out during a 7 years period. The aim of the study was to identify the most frequent causes of acute abdominal pain correlated with age, sex, onset of pain and other conditions in order to improve diagnosis and reduce mobility for mortality. Appendicitis was the most frequent diagnosis (75 pts = 16.4%). Non-specific abdominal pain (NSAP), found in 71 pts (15.5%), cholelithiasis in 57 pts (12.5%), abdominal malignancy in 47 pts (10.3%) were other frequent conditions. The largest number of admissions occurred in the age groups 60-70 years (16.6%) and 20-30 years (14.2%). Surgical operations were performed in 206 patients (45.7%). The overall mortality was 4.2% (19/450 pts) and the rate increased significantly in patients aged > 60 years. Postoperative mortality was 5.8% (12/206 pts) while mortality rate in non-operated patients was 2.8%. The causes of perioperative death included perforated peptic ulcer, abdominal malignancies (15.4%) and urgent colonic resections (9.4%). The duration of inpatients stay increased significantly with the age of the patients, including those with nsap. The results of the study indicate a need to review the methods of diagnosis of appendicitis and to obtain a better clinical performance in patients with nsap.