Spontaneous motor activity and physically undemanding conditioned suppression of drinking behavior were assessed in rats of 3, 12, 18 or 30 months (M) age. Initial spontaneous motor activity of 12 M rats was as low as that of 30 M rats and both were significantly lower than that of 3 M rats. The performance of 3, 12 and 18 M rats were similar to each other, whereas 30 M rats started to perform poorer after one week of training. It is concluded that the acquisition deficits observed here in aged rats occur only after 18 months age and appear to be independent of the subjects' reactivity to punishment and their activity prior to training. © 1976.