Using male Sprague-Dawley rats of different ages, simple motor activity was measured over three 4 min. runs in a square open field after ethanol (EtOH, 2 g/kg, intraperitoneally) or saline. The different groups consisted of 12 animals whose mean ages was 20, 40 and 60 days. Motor activity and blood ethanol levels were measured at 30, 60 and 120 min. after injection. Blood ethanol levels (measured after each run) decreased from 1st to 3rd run in 20 and 40 day groups and increased from 1st to 2nd run in the 60 day group, before decreasing. Activity data indicated: 1) decrease in motor activity the 3 runs by all saline and the 21 day EtOH groups, 2) initial lower activity induced by EtOH in all age groups, 3) lack of decrease in activity over 3 runs in 40 and 60 day EtOH groups. All saline and EtOH age groups showed within-run decrease of activity.