Right atrial myxoma is a heart benignant tumor characterized by an important clinical polymorphism. We report a case of a 30-year-old female with a diagnosis of a big right atrial myxoma. The diagnosis has been done by transthoracic echocardiography which showed an important tumorous mass in the right atrium. It was moving, inhomogeneous and takes over the whole of right atrium cavity. The surgical excision of the tumor has been done under extracorporal circulation. The patient died after a second intervention for tricuspid failure.