Pulmonary embolism (PE) is a life-threateningcondition or complication frequently seen aftersurgeries. Despite its all fatal potency, the clinicalmanifestation of PE is neither sensitive nor specific.Therefore it could be easily underdiagnosed oroverdiagnosed, PE could be considered as one of theworst nightmares of cardiac surgeons.Decreasing the mortality from PE depends on rapidand accurate diagnosis, which should be based onobjective evidence. Risk factors for venous thromboembolism, diagnosticvalues of symptoms and signs and the new diagnostictechnologies are discussed, and a practical algorithmon PE diagnosis is presented in this review.Key words: Pulmonary embolism, deep vein thrombosis,heart disease, thromboembolism, open heart surgery,surgical complication