Cardiosurgical operations remain one of the most demanding and complicated surgical procedures. Cardiac arrest before extra corporeal circulation (ECC) is one of severe intraoperative complications which can occur in any moment of operation. We have tried to evaluate possible risk factors of intraoperative, pre-ECC cardiac arrest in cardiac surgical patients and also have tried to estimate, if such an incident itself can be a risk factor for further post-operative complications. Pre-ECC intraoperative cardiac arrest (ICA) has occurred in 28 (aged 34-9) of 1,288 cardiac surgical patients operated on in our institution between July 1998 and December 2001. In 20 of these patients (71%) CABG was a planned procedure and in the remaining eight heart valve prostheses implantation were planned. In all 28 cases ventricular fibrillation was a cause of ICA and all patients required indirect and/or direct cardiac massage up to the moment of ECC start. In the subgroup with coronary artery disease (CAD) eight patients (35%) had left main stenosis, 13 (46.4%) had myocardial infarction in medical history. In the group of valve patients mitro-aortis valve disease was diagnosed in three cases and mitro-aorto-tricuspid valve disease with CAD or mitral valve disease or aortic valve disease in single patients. ICA was the most frequent during sternotomy (eight cases), pericardium opening (seven cases) and harvesting of left internal mammary artery (LIMA). In 16 cases prolonged reperfusion was necessary after declamping of the aorta, and in two of these cases ECC re-entry was needed. Eight patients (28.6%) have died, in 14 cases (50%) low output syndrome has been diagnosed, in five cases (18%) myocardial infarction has occurred and, in nine cases (32%) different neurological complications have been found postoperatively and five patients required resternotomy. All these complications were significantly more frequent in the investigated group than in the whole population of patients. We conclude that pre-ECC ICA contributes to noticeable post-operative complications rate increase. Sternotomy and opening of pericardium are the most frequent moments when pre-ECC ICA appears. We have not found any significant preoperative risk factors for pre-ECC ICA.