With simple abdomen, double contrast colon study, and ultrasonography, authors retrospectively analyzed radiologic findings of 46 cases which were proved periappendiceal abscess, dut to periforation of appendix, by histology of follow-up ultrasonography from May in 1983 to Junly in 1985 at Yeung-Nam University Hospital. The results obtained were as follows: 1. Of 46 cases, 24 cases were males and 22 cases females, with the results of above statistics, periappendiceal abscess was not influenced by sex. 2. Periappendiceal abscess was most frequently 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 in ultrasonography were detedted in B.E., i.e. sensitivity of B.E. is higher than that of ultrasonography. 5. Differences of ultrasonography and B.E. ultrasonography : acute, severe pt., no risk of leakage, no need of bowel prep ration, easy follow-up study, easy D.Dx. of mass nature B.E. : subacute, chrone pt., not influenced by abdominal gas, not require high skill, relatively high wensitivity and specificity, D.Dx. of fluid-filled bowel and abscess