Abstract : Even with advent of modern diagnostic tools, misdiagnosis of appendicitis has remained more or less constant. Percentage of misdiagnosis is higher among women than men and children than adults. We aimed to validate importance of AIR score in diagnosing acute appendicitis and comparing it with Alvarado score. This case series study was done in emergency and surgical department of Al- Kindy Teaching Hospital- Baghdad-Iraq during a period extended from second of January /2016 to 30/July/2017 were convenient sample of patients attended emergency unit suffering from acute abdominal pain with suspicion of acute appendicitis. Appendicitis inflammatory score (AIR) (at score>4) in comparison with Alvarado score (at score >4) shows that former has good statistical points of discrimination for diagnosing patient with acute appendicitis, with a sensitivity of 91%, and outclass Alvarado score, with a sensitivity of 83%. AIR versus Alvarado score former outperform result obtaining by later one in children below 12 year old with a sensitivity and specificity of 88% and 61%s respectively for AIR score (score >4), and a sensitivity and specificity of 41% and 61% respectively for Alvarado score (score >4). White cell count can be normal or low as a result of lymphopenia or sepsis. C - reactive protein (CRP) concentrate is a powerful indicator of appendicitis particularly complicated cases. CRP demonstrates a sensitivity of 85% and specificity of 69%. Rebound tenderness was demonstrated in 63% individuals in present study. This study validates AIR score in diagnosing acute appendicitis and exceeds Alvarado score.