Omental cysts are rare and occur in approximately one of 100,000 patients. About 25% of these cysts are presented in children less than 10 years of age. Symptoms produced by omental cysts are not clinically diagnostic and pre operative diagnosis is exceedingly difficult. Omental cysts producing clinical symptoms must be differentiated from other cysts and acute intra abdominal conditions such as pancreatic cysts, retroperitoneal cysts, ovarian cysts, cysts of the kidney, ascites, tuberculosis' peritonitis, and appendicitis. In some cases, these cysts are discovered in the course of an abdominal operation for some other reasons. Here, we report the case of a 6-year-old boy presenting with acute abdominal pain presenting a giant omental cyst in him during laparotomy.