The purpose of our study was to investigate the association between perioperative cerebral microembolization, expressed as high-intensity transient signals (HITS) and postoperative dynamics of the neuromarker S100P in patients operated using cardiopulmonary bypass, and to assess their impact upon the neurocognitive function in the early postoperative stage. The study involved 62 consecutive male patients aged 60 or above, alls scheduled for elective aortocoronary bypass. The patients were recruited from two groups with respect to the use of CPB: on-pump group (CPB+, N = 30) and off-pump group (CPB-, N = 32). In all patients we performed intraoperative monitoring of cerebral haemodynamics using transcranial Doppler, with the goal of quantifying perioperative cerebral microembolization. The serum levels of the neuromarker S100l were measured immediately after surgery, and then 12, 24 and 48 hours after the surgery. Neurocognitive status was assessed before and after the surgery and in three cognitive domains. Results of the study have shown that with respect to the short-term postoperative neurocognitive outcome there is no significant difference between the on-pump and off-pump surgical technique of coronary revascularization'. Perioperative cerebral microembolization was significantly more pronounced in the on-pump group yet it did not affect early postoperative neurocognitive function, while the increase in the neuromarker S100beta serum level 48 hours after surgery may have prognostic value as a predictor of postoperative neurocognitive dysfunction.