The influence of the D2-receptorblocker domperidone (DP) at a concentration of 1 microM was investigated on an electrically induced long-term potentiation (LTP) measured as the enhancement of the population spike (PS) amplitude in the hippocampal CA1. It could be shown that the drug does not influence the initiation but the maintenance of LTP. The results once again support the hypothesis that different phases of LTP exist which are realized by different cellular inputs.