A case of a 19 year-old woman in the third trimester of her second pregnancy admitted due to suspected of acute pulmonary embolism (PE) is presented. The diagnosis was confirmed by transthoracic echocardiography (TTE) which revealed an immobile wall-adherent thrombus in the left pulmonary artery. A complete regression of the thrombus was obtained after antithrombotic treatment. We conclude that TTE examination can be useful in diagnosing of PE and may be safely used during pregnancy.