It is hypothesised that newborns are affected by their foetal experience of the maternal heart beat present in utero. This study aims to verify whether, as a consequence of this prenatal experience, newborns show differentiated behavioural (non-nutritive sucking, NNS) and physiological (cardiac frequency, CF) responses in front of maternal and non maternal heart beat. If this happens, it is examined whether this discrimination is determined only by the complex structure of the maternal and non maternal heart beat or also by its isolated rhythmical component. 12 newborns were presented with the heart beat of the mother and of another woman, both prepared in two versions, i.e. with their complex structure and with only their rhythmical component. In 6 subjects both NNS and CF were recorded, while in the other 6 subjects only the CF was measured. The results obtained with the NNS response seem to confirm that the maternal heart beat in its complex structure is a significative stimulus for newborns and is differentiated by the non maternal one.