We report a rare case of coincidental left atrial and right ventricular myxomas manifesting as masses with different echodensities on transthoracic echocardiography. This patient had a history of left atrial myxoma, left intra-left internal carotid artery myxoma, and facial cutaneous myxoma 3 years prior to admission. A Carney complex was suspected, and the patient subsequently tested positive for PRKAR1A mutations. The patient was followed up regularly by a biannual echocardiography, which was free from abnormalities until the date of admission. A repeat transthoracic echocardiography revealed a massive left atrial mass of solid echodensity, and a minute hypoechoic entity in the right ventricular outflow tract. Both masses were confirmed for existence by an enhanced cardiac CT. Chest CT also revealed multiple pulmonary emboli. Successful surgical repair was performed revealing that both masses were hemorrhagic nipple-like lesions and that the pulmonary emboli were myxomatous in nature. Postoperative recovery was uneventful. Postoperative echocardiography showed a clear heart chamber, and the 1-year follow-up showed no abnormalities. Further research is needed to clarify the echocardiographic characteristics of multiple myxomas when they occurred simultaneously in different chambers.