Starting on the 7th day from birth, rats were given orally 0.1-0.2 ml per day of the carboxymethylcellulose solution with or without magnesium pemoline (MgPe) solved at the rate of 20 mg/20 ml. From the 28th or the 41st day, the rats were trained on a pattern discrimination task, motivated by electric shock; at the same time, the drug rats were given i. p. 20 mg/1 ml/kg of MgPe, and the control rats were similarly treated with the same volume of the solution without the drug prior to the daily session. Results indicated a significant facilitative effect of MgPe on pattern discrimination even when training started at the 28th or the 41st day. The drug rats ran significantly faster than the control rats but this time measure was not correlated with the learning measure. MgPe was also shown to faciliate reversal learning but failed to affect the retention of the original discrimination, possibly due to the ceiling effect.