Background: The purpose of this study was to clarify the dynamics of heart rate variability (HRV) in the dynamics of alcohol withdrawal syndrome relief. Methods: We examined 31 patients at an average age of 43. 9 ± 5. 2 years with alcohol withdrawal syndrome (the middle stage, the period of maintenance therapy) and 15 volunteers of comparable age. The control points for assessing HRV were 1 to 2, 3 to 5, 6 to 9, and 10 to 15 days after stopping alcohol consumption. Electrocardiography was performed using the software and hardware complex Polyspectr-12 (Neurosoft, Russia). HRV was evaluated using a set of statistical and spectral analytical methods, including the coefficient of variation (%), and spectral analysis indicators (based on the fast Fourier transform algorithm using all points without smoothing). The geometric analysis of the cycles of nonlinear cardiac rhythm waves was performed using a chaos test via the method of Gavrilushkin (2007). Results: In our patients with alcohol withdrawal syndrome in the rehabilitation period, there was a pronounced instability of the heart rhythm, which was manifested in the increasing role of its intracardiac regulation mechanisms and the stimulating effect of sympathicotonia. The most pronounced shifts in HRV were detected in the period from 3 to 9 days after the cessation of alcohol consumption. Additionally, the risk of arrhythmogenic complications in alcohol withdrawal syndrome was highest from the third to the ninth day of the rehabilitation period. Conclusions: Our patients with alcohol withdrawal syndrome in the rehabilitation period exhibited a pronounced instability in their heart rhythm, manifesting itself in the increasing role of its intracardiac regulation mechanisms and the stimulating effect of sympathicotonia.