BACKGROUND: Alcohol intoxication is associated with deterioration of cardiac nervous function and increased mortality. PATIENTS AND METHODS: Therefore, 14 patients (eight male, six female; 24-59 years) with pure ethanol intoxication and toxic levels of 210-520 mg/dl in the blood were prospectively investigated. For evaluation of changes in sympathetic and vagal modulation, an analysis of heart rate variability (HRV) was performed. RESULTS: The results show that HRV in general is suppressed in dependence on blood alcohol levels. Most correlation was found in short-term variability of frequency domain (HF power) after logarithmic transformation (p < 0.001). Also the discrimination of moderate versus severe intoxication was greatest in HF power (p < 0.001). During recovery, all HRV parameters increased to significantly higher figures within 24 h (p < 0.001), but elevated LF/HF ratio as a sign of sympathetic predominance continued over the whole observation period (p < 0.001 to reference). Regarding the danger of possibly life-threatening arrhythmias, the LF/HF ratio showed significantly increased figures in the period of maximal development of supraventricular and ventricular arrhythmias (p = 0.001 to 24-h mean of LF/HF). CONCLUSION: These results underline the longer-lasting hyperadrenergic state during "holiday heart syndrome". The still depressed cardiac autonomic nervous system after 24 h, especially in the vagal activity-describing part, might be basically relevant for later occurrence of cardiovascular complications, if additional trigger factors become present.