Acute appendicitis is an important differential diagnosis in patients with right iliac fossa pain and the accuracy of its diagnosis has remained a problem in patients with equivocal signs. This is a prospective hospital based study to evaluate the diagnostic accuracy of the Bengezi and Al – Fallouji modified Alvarado score in predicting appendicitis for patients with right iliac fossa pain. The Alvarado score is a simple scoring system that incorporates three symptoms, two signs and two simple blood investigations for predicting the diagnosis of acute appendicitis. A total of 128 consecutive patients who presented in the Accident and Emergency Department of the University of Port Harcourt Teaching hospital from June 2002 to May 2003 were studied. Thirty – eight patients with scores less than 4 after observation of eight hours and re-evaluation at Accidents and Emergency were discharged without surgery and reviewed in the outpatient clinic weekly for a period of one month. Eighty-eight patients had appendicectomy performed and their Modified Alvarado score computed from the research protocol and studied. Eighty patients had inflammed appendix and the negative appendicectomy rate was 9.09%. One hundred and five patients operated on for suspected acute appendicitis without scoring from June 2003 to May 2004 were used as controls. The negative appendicectomy rate in the control group is 19.05%. The Alvarado score showed high sensitivity of 92.93% and specificity of 92.93% in predicting the diagnosis of acute appendicitis in this study. The symptoms with high validities are migrating pain with sensitivity of 72.5%, accuracy of 69.5%, nausea with sensitivity of 73.8% accuracy of 69.3% and anorexia with sensitivity of 72.5% and accuracy of 69.3%. Right iliac fossa tenderness with sensitivity of 100%, accuracy of 100% and rebound tenderness with sensitivity of 97.5%, accuracy of 89.8% were most sensitive signs. Combination of the clinical features augments and improve the diagnostic accuracy of acute appendicitis. The Bengezi and Al – Fallouji modified Alvarado score is a useful tool in the diagnosis of acute appendicitis, especially at both ends of the scale and it is easy to work with. The mortality rate in this study was zero.