Objectives: Evaluation of the diagnostic  yield of preoperative abdominal  CT imaging of patients presenting  by acute right lower abdominal  pain and the probability for reduction of negative appendectomy rates in these patient. Patients & methods: The present study aimed to include patients presenting with acute right lower abdominal  pain who were admitted as acute abdominal emergency  under observation. All enrolled patients underwent clinical examination and laboratory investigations to provide a probable clinical diagnosis.All patients underwent abdominal ultrasonography (US) and then scanning with multi-detector  row CT. All patients with clinical suspicion for need of surgical exploration underwent laparotomy and excised specimens were examined pathologically. Patients who became stable with negative US and/or CTwere maintained under-observation till 24 hours and were discharged. Results: One hundred and seventeen patients underwent surgical exploration including 81 patients who had emergency surgery and 36 who had surgery on elective basis during observation period. Pathological examination confirmed positive diagnosis of acute abdomen in 78 patients and 39 patients were pathologically free (Negative laparotomy).Clinical  diagnosis defined 79, abdominal US defined  83 and CT defined  74 patients  as having  positive  acute abdominal condition. Preoperative CT showed a significantly higher test validity characters in comparison to abdominal  US and clinical examination with sensitivity rate of 94.6%,  specificity  rate of 90.7% and accuracy rate for diagnosis of93.2%. Statistical analysis defined preoperative CT as the best predictor for negative laparotomy. Conclusion: Preoperative CT for patients with acute right lower abdominal pain reduces the negative laparotomy rate, improves true positive surgical rate and is mandatory especially in suspicious cases. Moreover, preoperative CT could help di.fforential diagnosis of the underlying pathology and so can modify surgical decision