Bleeding is the most common and serious complication of thrombolysis in ST elevation myocardial infarction. Most bleeding cases are associated with an intervention or operation, but spontaneous bleeding such as gastro-intestinal bleeding or intracranial hemorrhage can happen. This is a report on the case of a 76-year-old female patient with retroperitoneal hemorrhage due to spontaneous right colic artery branch bleeding after thrombolysis in ST elevation myocardial infarction.