Although the ultrasonography has been regarded as a important procedure in the diagnosis of intraabdominalabscess, there were relatively few papers concerning the ultrasonographic findings of periappendiceal abscess.Nineteen cases of surgically proven periappendiceal abscess caused by perforated appendicitis were studied byultrasonography at the Kyung Hee University Hospital during last 34 months. The results were as follows; 1.Diagnostic accuracy of the real-time ultrasonography was 94.7%(18/19). There were only one false positive and onefalse negative. 2. The location of abscesses were ; periappendiceal 68.4%(13/19), pelvic 21.0%(4/19), subhepatic5.3%(1/19) and subphrenic 5.3%(1/19) in order of frequency. 3. Variable echo-patterns of abscesses wereencountered. But irregular, thick walled, posteriorly reinforcing, echo-free or mixed echo-patterns were mostcommon.