Objectives: To determine the diagnosis accuracy of total leukocyte count in acute appendicitis keeping histopathology as gold standard. Material and Methods: The study was performed in Department of General Surgery Lady Reading Hospital, Peshawar from 16th February 2016 to 16th august 2016. In this study a total of 163 patients were observed. Complete history, physical examination, and investigations (KUB), ultrasound abdomen were performed. Decision regarding appendicectomy was made by a single consultant surgeon based on his clinical assessment. All the included patients were prepared for surgery to be operated on the elective list next day same consultant surgeon. Post operatively the appendix specimen was collected, preserved in formalin solution and sent to a single expert histopathologist. The patient's histopathology reports were followed up for in outpatient department. The exclusions criteria was strictly followed to control confounders and exclude bias in the study results. Results: Our study shows that mean age was 32 years with SD ± 7.84. 38% patients were male while 62% patients were female. Diagnostic accuracy of AP on total leukocyte count and histopathology as gold standard was analyzed as the sensitivity was 78%, specificity was 27%, Positive predictive value was 94%, Negative predictive value was 8% and the overall diagnostic accuracy was 75%. Conclusion: Our study concludes that total leukocyte count had sensitivity 78%, specificity 27%, Positive predictive value 94%, Negative predictive value was 8% and the overall diagnostic accuracy was 75% in the diagnosis of acute appendicitis. [ABSTRACT FROM AUTHOR]