Background: Acute appendicitis, the most common surgically correctable cause of abdominal pain, the diagnosis of which remains difficult in many instances and is essentially clinical. However a decision to operate based on clinical suspicion alone can lead to removal of normal appendix in 15–30% cases. Several diagnostic scoring systems have been devised as an aid to early diagnosis of acute appendicitis and to reduce the incidence of negative appendicectomy. One such scoring system was described by Alvarado and later modified by Kalan et al. The present study is attempted to evaluate the efficiency of modified Alvarado score in pre–operative diagnosis of acute appendicitis. Methods: One hundred twenty consecutive patients suspected of acute appendicitis that were admitted, investigated and treated were taken for the study. After detailed examination and investigations a modified Alvarado score was applied to these patients. They were assigned in three groups and were treated accordingly. Results: The result of the study showed that high scores in men and children (7–9) had a sensitivity of 92.3% and 83.3% respectively, whereas in females it had a sensitivity of 72.7%. The score (5–6) in males and females had a sensitivity of 57% and 50% respectively. Conclusions: The high scores in modified Alvarado score is dependable aid in the early diagnosis of acute appendicitis in men and children but it’s not true as far as women are considered. Ultrasonography of abdomen is a useful tool in avoiding negative appendicectomy rates particularly in females.