Background: Diagnosis of acute appendicitis depends mainly on the surgeon’s skills, as there is no single test that can confirm or rule out diagnosis, most of cases are first met by young surgeons in the emergency departments, so a diagnostic score which is easy applicable with good diagnostic accuracy was needed, ALVARADO and modified RIPASA scores are known but none of them proved to be better than the other. Patients and method: ALVARADO and modified RIPASA scores were applied simultaneously on 224 patients with right lower quadrant pain, results of the scores were compared to the results of histopathological examination of the appendectomy specimen. Results: ALVARADO score has positive predictive value (PPV) 100%, negative predictive value 36.5%, (NPV), sensitivity 66.3%, specificity 100%, and diagnostic accuracy 71.8%. Modified RIPASA score has positive predictive value (PPV) 90.4%, negative predictive value (NPV) 92.3%, sensitivity98.9%, specificity 55.8%, and diagnostic accuracy 90.6%. Conclusion: ALVARADO score is more specific, but modified RIPASA score is more sensitive, in diagnosis of acute appendicitis, if both scores were applied together to all patients presented with acute right lower quadrant pain a better accuracy could be obtained, that can decreases negative appendectomy rate.