A prospective study was conducted to assess the frequency of acute appendicitis at different phases of menstrual cycle, 508 patients presented with acute right lower abdominal pain diagnosed as acute appendicitis and submitted to appendectomies at Basrah Teaching Hospital during a two years period from October 2000 to October 2002. There were 263 females with mean age of 25 years and 245 males as a control with the mean age of 27 years. The study reveals a higher incidence of normal appendixes were removed among females 46 patients (17.5%) as compared to 12 (4.9%)in males. Most of normal appendixes occurred during follicular phase 27 patients (58.7%) as compared to other phases. There were 23 females with normal appendixes have no any associated pathology, 20 patients (86.95%) of them were occurred around the mid cycle (day 12-16). There was difference in the incidence and the severity of acute appendicitis among different phases of menstrual cycle. It appears that the frequency of acute appendicitis was highest in the luteal phase 105 patients (61.77%) compared to other phases, while most of perforated and gangrenous appendixes occurred during menstrual and follicular phases, 13 patients (36.11%), 15 patients (41.66%) respectively.