Standardized investigations on resting heart rate variability (HRV) should provide more information on acamprosate's human pharmacodynamic properties because acamprosate interacts with several neurotransmitter systems which are also involved in maintaining autonomic neurocardiac balance. We performed HRV measurements prospectively in 69 healthy controls and 19 chronic alcoholics to prove the hypotheses that: (1) compared to healthy controls, chronic alcoholics show disturbances in neurocardiac vagal function; and (2) in alcoholics, acamprosate treatment (6-8 days) should further decrease parasympathetic activity if acamprosate interacts with central gamma-aminobutyric acidA receptors in vivo. Cardiovagal dysfunction was initially present in 21% of the alcoholics. After treatment. however, their neurocardiac sympathetic-parasympathetic balance improved significantly.