Syncope is a common presentation in the neurology clinic and emergency room. However, pulmonary embolism (PE) as a cause of syncope is not common or well recognized. Four aged patients presented to our clinic with episodic syncope, and PE was finally identified as the underlying cause. The significant clinical presentations included transient loss of consciousness and hypoxemia on admission. Syncope with hypoxia should therefore be highlighted as an important clue to the diagnosis of PE in aged patients. A negative D-dimer test will be encountered in patients with a very short history. Repeated D-dimer testing is necessary.