Alcohol use in children and adolescents is widespread. However, very little is known about the effects of alcohol exposure during this period of postnatal development. The goal of the present study was to compare the relative sensitivity to the sedative effects of alcohol in periadolescent and adult rats. After treatment with either 4 or 5 glkg ethanol, both 20- and 30-day-old rats regained their righting reflex significantly earlier than 80-day old rats. In 30-day-old rats, serum ethanol concentrations (SECs) were significantly greater at the time of the recovety of the righting reflex than 80-day-old rats. Developmental differences in the effects of ethanol on locomotor activity were also observed. In 60-day-old rats, 2.5 glkg ethanol generally decreased locomotor activity. Ethanol did not significantly alter locomotor activity in 20- and 30-day-old rats. Finally, there were sig nificant developmental differences in the pharmacokinetics of ethanol with a significant delay in the time to peak SECs in 80-day-old rats relative to 20- and 30-day-old rats. These findings indicate that periadolescent rats are less sensitive to the sedative effects of ethanol as they recovered their righting reflex earlier and at significantly higher SECs than adult rats.