The authors present a 76-year-old female with high blood pressure and hypercholesterolaemia as cerebrovascular risk factors, who received intravenous thrombolysis for an ischaemic stroke with a progressive neurological improvement. She was asymptomatic at 48 h and she was transferred to the neurology department where antithrombotic treatment was initiated. She began to sit the following day when she suffered a massive pulmonary embolism (PE). Cardiological study showed patent foramen oval persistence and the presence of an atrial septa aneurysm, and paroxysmal atrial fibrillation. The delay of the onset of the antithrombotic treatment could have been determinant for the massive PE. Thromboembolic complications may be seen after intravenous thrombolysis for ischaemic stroke. An accurate treatment is needed in order to avoid potentially threatening complications such as massive PE.