The behavioral and biochemical effects of amantadine hydrochloride (ATD) on some ethanol (ETOH) mediated responses in rats and mice were studied. Administration of ATD, 0.5 mM/kg IP, prior to a narcotic dose of ETOH significantly decreased the central depressant action of ETOH, as measured by the duration of ETOH-produced narcosis in mice. The time required for the onset of ETOH-narcosis was significantly delayed in ATD-treated mice compared to controls. Analyses of whole blood and brain ETOH concentrations showed that ATD-treatment prior to ETOH significantly reduced brain content of ETOH from saline-pretreated mice at the time of onset of ETOH narcosis as well as 30 min after ETOH injection without concomitant change in blood ETOH concentrations at the respective time intervals. Administration of ATD 0.5mM/kg IP, reduced voluntary intake of ETOH by rats voluntarily selecting 5% ETOH solution over water as the drinking fluid. There were no changes in cytoplasmic rat liver alcohol dehydrogenase (L-ADH) and mitochondrial aldehyde dehydrogenase (L-ALDH) activities in rats maintained on water or 5% ETOH as the drinking fluid and administered ATD, 0.5 mM/kg IP, once or identical dose once daily for six consecutive days. However, ATD produced in vitro non-competitive inhibiton of both L-ADH and L-ALDH at a concentration range between 10(-3) M and 3 x 10(-3) M assay mixture. The results indicate the potency of ATD in negating ETOH-mediated responses measured and suggest for a possible clinical trial for ATD in the management of alcoholic patients provided it is devoid of disulfiram-like reaction in man.