With simple abdomen, double contrast colon study, and ultrasongraphy, authors retrospectively analyzedradilogic findings of 46 cases which were proved periappendiceal abscess, due to perforation of appendix, byhistology or follow-up ultrasnongraphy from May in 1983 to July in 1985 at Yeung-Nam University Hospital. Theresuls obtained were as follows: 1. Of 46 cases, 24 cases were males and 22 cases females, with the results ofabove statistics, periappendiceal abscess was not influenced by sex. 2. Periappendiceal abscess was mostfrequently demonstrated in forties. 3. Comparison of ultrasonography and B.E. Pseudorenal pattern(Ultrasonography)- well defined defect (B.E.) Cystic pattern(Ultrasonography)- serrated defect (B.E.) 4. Missed 2 cases inultrasonography were detected in B.E., i.e. sensitivity of B.E. is higher than that of ultrasonography. 5.Differences of ultrasonography and B.E. - ultrasonography - - B.E. - acute, severe pt. subacute, chronic pt. norisk of leakage no need of bowel preparation easy follow-up study easy D. Dx. of mass nature not influenced byabdominal gas not require high skill relatively high sensitivity and specificity D. Dx. of fluid-filled bowel andabscess