Floating cardiac thrombi are peripheral and pelvic venous clots which on their way to the lungs, are accidentally lodged in the heart. They are rare but clinically significant because of the high incidence of massive pulmonary embolism and high mortality. Two patients, one with snake-like thrombus in the right atrium and one with snake-like thrombus in the left atrium stuck in the open foramen ovale, are presented and discussed. The significance of early echocardiographic examination in suspicion of pulmonary embolism is stressed. If there are floating emboli in the heart, emergency care is required, but there is no clear consensus regarding the optimal therapeutic approach.