Atrial myxoma is the most common primary cardiac tumor. We report the case of left atrium myxoma accompanied by severe thrombocytopenia in a 72-years-old woman. The thrombocytopenia has been discovered 5 years ago, it was explored, no obvious cause was found, the diagnosis of idiopathic thrombocytopenia was retained based on clinical and paraclinical arguments, corticosteroid treatment was ineffective and platelet count remains low. Complete surgical excision of the mass was performed. Platelet count was gradually increased to reach 95 103/µl after 6 months postoperatively. In this report, we highlight that thrombocytopenia might be one rare hematological manifestation of myxoma but need more cases for support. By illustrating this association, we hope to facilitate an earlier diagnosis of cardiac myxoma to treat and avoid complications of both thrombocytopenia and myxoma.