Meckel diverticulum is a vertigal remnant of the omphalomesenteric(vitellointestinal) duct.As a congenitaly anomaly it is a true diverticulum,ranger from 1 – 12 cm in a lenghtand it found 45 – 90 cm proximal to the ileocecal valve.It is frequently heterotopic tissue(gastric mucosa accounts for 50%),occurs in about 2% of the general population.The cause of bleeding is mucosal ulceration,because the ectopic gastric mucosa produces hydrocholic acid.The male or female ratio of patients with symptomatic diverticulum is 3:1.The association between bleeding Meckel's diverticulum and bleeding ulcerative colitis is unknown in a hungarian pediatric literature.We describe the case of a 9 years old boy presented nausea,intermittal abdominal pain and rectal bleeding.He has not been earlier any illness.Total colonoscopy was done with biopsy. We diagnosed ulcerative colitis,the histological examination showed the presence of inflammation colonic mucosa (crypta abscess,signs of severe colitis).He had been transmitted in the intensive care unit with recurrence rectal bleeding.He received transfusion because of severe anaemia. Abdominal reultrasound examination was negativ.99mTc pertechnetate didn't localized bleeding place in the abdominal tract.After 5 days the new rectal bleeding indicated explorative laparatomy suspected Meckel's diverticulum despite of negative scintigraphy.Meanwhile of laparatomy we diagnosed Meckel's. diverticulum(10 cm lenght,45 cm from the ileocecal valve).The histology found ectopic gastric mucosa int he diverticulum.The diverticulum resection,appendectomy were made.The ulcerative colitis has been treated with medicament.The control blood test is negativ.He was descharged after 10 days laparatomy.The correct value of signs and new signs is very importent indicating conservative treatment or surgical intervention.