BACKGROUND Acute appendicitis affects human beings irrespective of age, nationality and region. Acute appendicitis is the most common surgical cause of emergency laparotomy. Considering the difficulties and challenges involved in accurate clinical diagnosis, there is a need for a validated, objective protocol for enabling the diagnosis. This study was carried out to validate the modified Alvarado score (MASS) and correlate with ultrasound and post-operative histopathological examination. METHODS This cohort study was carried out among 100 patients who were suspected with acute appendicitis. Upon clinical evaluation and ultrasound evaluation, Modified Alvarado Score was computed, and patients were taken up for laparotomy/laparoscopic surgery. The resected specimens were sent for histopathological examination. RESULTS Majority of the participants had a score >7 (74%) of which 51 were males, 21 were females and two were children. Ultrasound detected positive cases in 90% of the participants, while acute appendicitis by histopathology was present in 54% of the participants. There was a statistically significant correlation with Modified Alvarado score (p<0.0001). Negative appendicectomy was prevalent in 21% of the participants. CONCLUSIONS Modified Alvarado Scoring system is ideal for the diagnosis of acute appendicitis since it is simple to use, easy to apply and relies only on history, clinical examination and basic lab investigations.