Summary Introduction: Rhodiola rosea (RR) and Rhodiola kirilowii (RK) are well known for their influence on central nervous system, however their impact on the development of alcohol tolerance has not yet been proven. Objective: The aim of this study was to determine the ability of RR and RK roots extracts to inhibit the development of alcohol tolerance in vivo, both, peripheral (metabolic) and central ones. Methods: Male Wistar rats were treated with RR and RK extracts (p.o.) and ethanol (i.p.) for ten consecutive days. On the first, third, fifth and eighth days the hypothermic action of ethanol was measured, while on the ninth day the loss of righting reflex was examined. On the tenth day rats were treated with assigned extract and sacrificed 1 h after the ethanol injection. Results: Both extracts inhibited development of tolerance to the hypothermic action of ethanol. The observed effect seems to be specific since none of the extracts affected body temperature in water-treated animals. RK extract also prolonged the hypnotic action of ethanol. RR-treated rats had higher blood-ethanol concentrations, in contrast to RK ones. Conclusions: RR and RK extracts inhibited the development of tolerance to the hypothermic action of ethanol. Prolongation of the hypnotic action of ethanol by RK extract may be associated with influence on the central nervous system, while the RR one also inhibited the development of metabolic tolerance.