The accurate and early diagnosis of perforated appendicitis (PA) is important when a surgeon is making decisions with regard to time and method of operation that are critical in reducing morbidity and mortality. A total of 528 laparoscopic appendectomies were investigated with the review of data. Clinical factors for identifying PA and a comparison using computed tomography (CT) (prominent role in detection of appendicitis despite of its high cost) were done. Among the clinical factors, total duration of the symptoms before admission (cutoff value: 24.51 h, sensitivity/specificity 0.51/0.65) and highly selective C-reactive protein levels (cutoff value: 9.52 mg/L, sensitivity/specificity 0.80/0.69) had significance on PA (P=0.001) compared with the performance of CT (sensitivity/specificity 0.28/0.99). The total duration of the symptoms before admission and highly selective C-reactive protein levels were respectable predictors of PA compared with those when using CT, showing that it could be another diagnostic tool for identifying PA.