Introduction: Simple appendicitis can progress to perforation, which is associated with a much higher morbidity and mortality. So, surgeons have therefore been inclined to operate when the diagnosis is probable rather than wait until it is certain. Objective: This study is designed to evaluate the sensitivity and specificity of clinical examination in the diagnosis of acute appendicitis. Methods: The study included 866 patients of acute appendicitis who had undergone appendicectomy with preoperative diagnosis of acute appendicitis. They were analyzed retrospectively. The parameters evaluated were age/gender, clinical presentation (signs and symptoms) and total white blood cell counts. The operative findings were recorded and the inflammation of the appendix was graded into normal, acutely inflamed and gangrenous. Results: Clinical diagnosis was made correctly in 807 (93.2%) of the patients. White blood cells count ranged from 3.70 to 45.30 /mm 3 (mean 17.5353 /mm 3). It was <10,000/mm 3 in 133 (15.4%) patients. Conclusions: Clinical assessment is the best criterion to reach a confident diagnosis. Investigations may supplement the diagnosis but are never a substitute for it.