Male rats were injected with ethanol as a 25% solution (3.5 g/kg body weight) and then the duration of the retention of the righting reflex (DRR) as well as the duration of ethanol-induced sleep (DEIS) were recorded. On the basis of DEIS in 60 rats, we selected four groups of six rats each: short-sleep group (SS, 34 +/- 5 min), intermediate-sleep (IS, 118 +/- 3 min), long-sleep (LS, 186 +/- 5 min) and non-sleep rats (NS, 0 min). The striatal crude mitochondrial fraction was assayed for acetylcholinesterase activity (AChE, EC 3.1.1.7) and high-affinity choline uptake. NS rats manifested similarity of the above parameters to those determined in SS and IS rats. LS rats were distinguished by a higher AChE activity in comparison with NS animals.