In the diagnosis of pulmonary embolism, the patient's medical history is of great importance, and the possibility of embolism must always be evaluated. Although symptoms such as shortness of breath, cough, bloody sputum, and chest pain may suggest pulmonary embolism, these can also occur in many other chest diseases. If the patient's history, the sudden onset of symptoms, and identified risk factors strengthen the suspicion of pulmonary embolism, the first step should be a simple blood test called D-dimer. D-dimer levels typically rise in pulmonary embolism; however, they are not sufficient for a definitive diagnosis on their own. A definitive diagnosis is established with a computed tomography (CT) angiography of the lungs, performed with a contrast agent (dye) according to the embolism protocol. This imaging method allows us to determine the location of a clot in the pulmonary arteries. To identify the source of the clot, Doppler ultrasonography of the legs may be performed. Once pulmonary embolism is definitively diagnosed, a treatment plan appropriate for the patient's clinical condition is formulated.