Acute appendicitis is one of the most common diseases which need to surgical intervention. And it is one of the most perplexing diagnostic problems comfronting physicians, often present with atypical finding that make accurate preoperative diagnostic technique. This is a prospective study on 240 patients admitted with right lower quadrant pain and operated for suspected appendicitis at the Department of Surgery Chung-Ang University Hospital from March 1, 1996 to February 28, 1997. Each case was divided into two groups according to whether the pathologic diagnosis was appendicitis or non-appendicitis. And each group analysed by the clinical presentation of the physical findings and the results of preoperative routine laboratory studies including leukocyte count and urinalysis. The result were as follows: 1) Over all of the diagnostic accuracy was found to be 75.8%.The negative appendectomy rate in female was 31% compared to 18% in male, and that was statistically significant. 2) Among negativeappendectomy cases, the number of female was always larger than male in all age groups and this observation was statistically significant in second to fourth decades. 3) Negative appendectomy rate of operated group after 72 hours from symptom developed was 49% compared to 32% of operated group within 72 hours from symptom developed, and that was statistically significant. 4) Statistical significant solitary affecting factor is leukocytosis, migration pain, rebound tenderness and that these parameters were potmtially good indicators of acute appendicitis, second to fourth decades female, the time frome symptom onset to operation over 72 hours, and that these parameter were potentially indicators of non-appendicitis.