A growing body of evidence has recently accumulated suggesting that several unfavorable cardiovascular events, e.g., myocardial angina and infarction, sudden cardiac death, and stroke, present a specific temporal pattern in their occurrence. This has also been shown to be true for fatal pulmonary thromboembolism, with a high frequence peak in winter and in the morning hours. The authors report the circannual and circadian aspects of pulmonary thromboembolism, analysing both the temporal patterns of the underlying favouring or precipitating factors, and the possible therapeutic implications.