Abstract Background Appendicitis is most common general surgical emergency with a life time risk of 7%.Appendicitis is considered as disease of the younger age group with only 5-10% of cases occurring in the elderly population. Ultrasound and CT scan are helpful in diagnosing acute appendicitis.The rationale of this study is to find out the group of patients based on the Alvarado score that will certainly benefit from the use of city scan. As CT is the preferred imaging modality in diagnosing acute appendicitis. Alvarado score is used to stratify patients into a subgroup that will certainly benefit from CT use. Methods Cross-sectional validation study was conducted for six months from (30/03/2017) to (30/09/2017) in Surgical unit-1, holy family hospital, Rawalpindi. Alvarado score was calculated, and the patients then underwent a contrast-enhanced CT scan. For the data of CT scan, patients were divided into two groups Positive and negative of appendicitis. All selected patients underwent an appendectomy. Histological specimens were collected and interpreted. All the collected data was entered and analyzed on SPSS version 19. Results The mean age of the patients was 28.93±10.21 years. The male to female ratio was 1:1.1. The mean Alvarado score was 6.05±0.68. The sensitivity, specificity and diagnostic accuracy of CT scan for diagnosing acute appendicitis was 84.75%, 78.69% & 81.67% respectively taking histopathology as the gold standard. Conclusions According to our study CT scan is a reliable and useful diagnostic tool at Alvarado score of 5-6 in males and 6-7 in females, in predicting acute appendicitis keeping histopathology as a gold standard.