Abstract Objectives: To evaluate the diagnostic yield of preoperative estimation of serum C-reactive protein (CRP) and total leucocytic count (TLC) as adjuncts to modified Alvarado score (MAS) for diagnosis of acute appendicitis (AA) and prediction of cases of complicated appendicitis (CA). Patients & Methods: The study included 324 patients underwent appendicectomy; all patients underwent clinical examination and calculation of MAS and had abdominal ultrasonography (US). Blood samples were taken for estimation of serum CRP and TLC. Patients were categorized according to intraoperative findings into: CA including those had suppurative, gangrenous and/or perforated appendix, had appendicular abscess or mass and Uncomplicated appendicitis (UA) included patients had edematous or normal appendix. Results: MAS defined 107 patients had score 10,000 cells/ml in 193 patients, was 10 mg/l was defined in 230 patients, while 94 patients had serum CRP of