Cholinergic mechanisms in the hippocampus seem to play a role in memory function. Since it is well known that chronic alcoholics often have a disturbed memory function, the cholinergic activity of the hippocampus has been measured in 20 chronic alcoholics and 14 controls, post-mortem. Of the alcoholics, 13 were classified as "intoxicated" alcoholics and 7 as "sober" alcoholics, i.e., without ethanol in blood or urine at the time of death. A lower, although not significantly lower activity of the enzyme choline acetyltransferase (ChAT, presynaptic marker) was measured in the hippocampus of the chronic alcoholics as compared to the control group. A trend towards a lower number of muscarine-like binding sites was also observed for the alcoholic group, but was only significant for the oldest group of alcoholics (59-68 years; -30%; p less than 0.01) in comparison to controls. No significant change in the number of nicotine-like binding sites was found. A normal aging process with degenerative nerve cell changes might, in combination with an excessive intake of ethanol, lead to the more pronounced decrease in muscarine-like binding sites found for the older alcoholics.