Modified Alvarado scoring system was evaluated regarding its usefulness in the early diagnosis of acute appendicitis and in reduction of the incidence of negative appendicectomies. One hundred and ten patients with a provisional diagnosis of acute appendicitis were studied prospectively at R G Kar Medical College and Hospital, Calcutta over a period of 10 months. High score was found to be a dependable aid both in the pre-operative diagnosis of acute appendicitis and in the reduction of negative appendicectomies in men and children but the same was not true for women who had a high false positive rate for acute appendicitis.