Introduction: Acute appendicitis is a common emergency condition in paediatrics with different ages.The perforated appendicitis is one of the most serious complications of acute appendicitis which may lead to peritonitis. The aim of our study is to calculate the incidence of perforated appendicitis. Methods:This is a retrospective cross-sectional study has been conducted at Khartoum north teaching hospital.The total number of patients was 214. Results: the most common age in this study are 13 years old and the mean age is 11 years, 128 of cases were male 59.8% and 86 were females 40.2%. All cases of our study presented with fever 100%, 80.8% presented with right iliac fossa pain, and anorexia 100%. 50.5% of cases came within the first day of presentation and 26.6% of cases came in 4 th day of presentation, all cases presented with right iliac fossa tenderness, 15.9% of cases presented with perforated acute appendicitis, 67.29% of cases operated after 6 hours, 5.61% operated in more than 6 hours and 27.1% operated after 6 weeks. Conclusion: In this study the incidence of perforated acute appendicitis was 15.9% which is low in comparison with another study because there was no delay in appendectomy operation and the majority of patients came within the first day of the disease.