A retrospective survey was undertaken of 142 adults who had undergone cardiac surgery with cardiopulmonary bypass. According to the manufacturer's instructions for thromboelastography, patients were identified as showing evidence of fibrinolysis if after coming off bypass the Ly30 index was ≥7.5%. In the 20 fibrinolytic patients, fibrinolysis was readily corrected by tranexamic acid but these patients needed more colloid and more vasopressor support than the non-fibrinolytic patients. There were three deaths, all in the fibrinolytic patients. It is possible that fibrinolysis is a marker for onset of systemic inflammation syndrome. It is recommended that, until the association between fibrinolysis and worse outcome is investigated further, patients showing fibrinolysis early after cardiopulmonary bypass should not be discharged too soon from intensive care.