128 patients aged from 2 to 18 with symptoms of acute appendicitis were studied prospectively. Surgical procedure was performed in 58 patients (i.e. appendectomy). In 5 patients surgical findings were catarrhal inflammation, in 14 phlegmonous, in 9 gangrenous, in 15 perforated and in 13 no inflammation occurred. In 2 cases abscess periappendiceal was found intraoperatively. We considered as visualized only those appendices that were intraoperatively found at places ultrasonographically described. Ultrasonographic visualization was successful in 91.37%. The most relevant criteria for ultrasonic evaluation of the inflammation is noncompressibility noted in 97.67% of cases of appendicitis. The second criteria is thickened wall noted in 86.04% of patients. Ultrasonographic diagnosis of the abdominal fluid collections is confident: sensitivity 0.85, specificity 0.91. The diagnostic value of ultrasound findings in acute appendicitis is high: sensitivity 0.87, specificity 0.84. That is why routine ultrasound diagnostic examination in acute atypical appendicitis is recommended.