Spontaneous intramedullary hematoma (IMH) is a rare condition. The initial clinical manifestations are variable. Early symptoms of high thoracic IMH include thoracocervical pain that can be mistaken for emergent cardiopulmonary conditions such as myocardial infarction, pulmonary embolus, and aortic dissection. We report on a 34-year-old man who presented initially with chest pain and radiating pain in both shoulders. He was initially misdiagnosed as having a myocardial infarction and treated with heparin. Two hours after admission, correct diagnosis of IMH was based on the repeated neurologic examination and spine magnetic resonance imaging study. The patient underwent emergency surgical decompression and hematoma removal. We draw the misdiagnosis to the attention of the emergency physicians because early recognition of spontaneous IMH is very important for early surgical decompression to improve the prognosis.