For the evaluation of acute appendicitis many diagnostic methods such as physical ex-amination laboratory findings plain abdomen and barium enema have been widely used. But the overall accuracy was ranged from 50% to 84% and negative appendectomy rate was reported between 5% and 35% In these days resolusion ultrasonography is well known to be a good imaging modality in evaluation of acute appendicitis and its complications. Using high resolution ultrasonography 138 patients with right lower quadrant abdominal pain were examined for 16 months. The results were compared to post-operative findings and clinical follows: 1. the sex distribution of cases were 58 males and 80 females and most common in the third decade(33.3%) 2. The positice ultrasonographic findings were in 69 cases(50%) those were simple appendi-citis without complication in 46 cases (66.7%) acute appendicitis with periappendicitis in 9 cases (13.0%) acute appendicitis with abscess in 6 cases (8.7%) acute appendicits with appendicolith in 4 cases (5.8%) and perforated appendicitis in 4 cases (16%) 3. The ultrasonographic findgs of normal appendix were in 69 cases(50%) those were nonvisualization of appendix in 62 cases (91.3%) and visualization of normal appendix with single thin echogenic wall in 6 cases(8.7%) 4. In the 50 cases of control group the visualization of normal appendix on ultrasonography were in 8 cases (16%). 5. The ovarall accuracy was 95.7% with 97.1%of sensitivity and 94.4% of specificity.