Background and objectives: 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 diagnosis scoring systems have been devised as an aid to the early diagnosis of acute appendicitis and to reduce the incidence of negative appendisectomy. One such scoring system was described by Alvarado and later modified by Kalan. The present study is attempted to evaluate the efficiency of modified Alvarado score in pre-operative diagnosis of acute appendicitis. Methods: A hundred consecutive patients suspected of acute appendicitis who are admitted, investigated and treated are taken for 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 results of the study showed that high score in male (7- 9) had a sensitivity of 94.29 % where as in females it had sensitivity of 75.75 % respectively. The score (5-6) in male and female had a sensitivity of 90 % and 100 % respectively. Interpretation and conclusion: The high score in modified Alvardo score is dependable aid in the early diagnosis of acute appendicitis in male and but has limitations in young women. Ultrasonography of abdomen is a useful tool in avoiding negative appendisectomy rates.