The effect of a combined treatment with ethanol and imipramine or amitriptyline was tested in mice and rats. The antidepressants were given in one or, in some experiments, in 21 daily doses of 10 mg/kg each. In mice the effect of antidepressants was tested on acute toxicity, disturbances of rota-rod performance, hypothermia and sleeping induced by ethanol, in rats the effect of the antidepressants on the development of tolerance to sleep-inducing and hypothermic action of ethanol was investigated. Amitriptyline showed a tendency to pontentiate the ethanol-induced acute toxicity, while imipramine did not change it. Given in a single dose the antidepressants have a tendency to potentiate the impairment of motor coordination induced by ethanol, but after a prolonged administration did not influence the ethanol effect in the rota-rod test. The antidepressants enhance ethanol-induced hypothermia and prolong the ethanol sleeping time. The development of tolerance to hypnotic effect of ethanol in rats is not affected by amitriptyline and imipramine, but the antidepressants prevent the development of tolerance to hypothermic effect.