Of interest in case of sub-massive PE (sub-MPE), which is also associated with a quite high mortality (up to 8%) some disagreement concerning the best treatment modality still persists. Several authors support an intensive treatment modality favourizing the systemic i.v. thrombolysis; however, others suggest a more conservative attitude (anticoagulation alone with fibrinolysis only in case of clinical deterioration). These cases of sub-MPE may be very challenging, because an established consensus of the definition of sub-MPE combining clinical, radiological and cardiological criteria are still lacking. Furthermore the thrombolytic regimen is not complication-free, suggesting that, before performing an i.v. thrombolysis, the physician in charge of the patient has to seriously take in consideration all the absolute and the relative contra-indications of such a treatment. (i.e.recent surgery, active peptic ulcer, intra-cerebral bleeding, pregnancy, neoplasm, see Table 1).