The aim of the study was to assess the sympathovagal balance in group of 27 patients without significant structural heart disease after an attack of atrial fibrillation. The investigation was performed using spectral analysis of heart rate variability during examination under conditions of different orthostatic loads in single phases, called the supine-standing- supine test. The findings were compared with a group of healthy persons. These revealed a significantly decreased total spectral power (430.7 vs 1558.0 ms(2) supine1; 477.6 vs 1042,5 ms(2) standing; 567.5 vs 1948.5 ms(2) supine2), and spectral power of the high frequency spectral component (140.8 vs 619.3 ms(2) supine1; 96.2 vs 203.3 ms(2) standing; 186.3 vs 739.4 ms(2) supine2) in the studied group of patients in comparison with the control group.