Background. It is known that after coronary artery bypass graft surgery (CABG) heart rate variability (HRV) becomes significantly decreased with a gradual recovery in a few months after surgery. However, literature data about the impact of the off-pump CABG on postoperative HRV are not complete. Therefore, the aim of this study was to analyze postoperative value of HRV in CABG patients operated on with off-pump versus on-pump coronary surgery. Methods. This study included 206 consecutive patients who underwent CABG. Sixty six patients (32%) were operated on off-pump while 140 patients (68%) were operated on using the machine for extracorporal circulation. HRV was analyzed from 24-hours Holter electrocardiogram recordings. Results. No significant differences in postoperative values of HRV variables were found between off-pump versus on-pump CABG patients (Mean RR interval 885 +/- 106 versus 879 +/- 125 ms, standard deviation of all normal R-R intervals 107 +/- 30 versus 105 +/- 34 ms, NS, total power 2298 +/- 2472 versus 2156 +/- 1913 ms(2), NS). Conclusions. The results of the study showed that there are no differences in HRV few months after surgery between patients operated on with off-pump versus on-pump CABG.