Acute appendicitis is the most common acute surgical condition of the abdomen. When the clinical presentation is atypical , barium enema has proven to be safe and useful in confirming the diagnosis and reducing the negative surgical exploration. However, the performance of barium enema in acute appendicitis has known contraindication primarily because of fear of leakage by perforation of the inflammed appendix. This study using barium enema as a diagnositc aid in acute appendicitis with atypical clinical presentation was performed to further support the previously noted efficacy and safety of this procedure. The results were as followings : 1. In case of acute appendicitis with atypical clinical presentation , the use of barium enema as a diagnostic aid increased the accuracy of diagnosis and decreased the negative surgical exploration. In women between 11 to 50 years old age, especially , it played important role differentiating appendicitis from nonsurgical acute abdomen. 2. The results of the study were 92. 31% in sensitivity, 7.69 % in false postive, 6.9% in false negative, and 10.26% in negative appendectimy. 3. None of case of leakage of barium by perforation of the inflammed appendix was noted, therefore, barium enema was thought to be safe as a diagnostic aid in acute appendicitis. 4. A simple partial or nonfilling of appendix without other associated positive findings could not exclude appendicitis, therefore, close clinical observation was necessary. 5. The positive findings of barium enema and their sensitiveity were as followings : 1. Nonfilling of appendix : 90% 2. Partial filling of appendix : 91.7% 3. Displacement or a local impression on terminal ileum : 100% * In all cases, combined with a local impression on cecum and/or irritability of cecum or terminal ileum.