In order to investigate the effects of a deprivation of the nutritive sucking (NS) on the activity of non-nutritive sucking (NNS), we examined 8 infants (ages 1-13 months) continuously fed by intracaval catheter. They had no NS experience at all from birth. Eight age-matched normally fed infants served as controls. The infants were examined for a full 24-h period by polygraphic recordings and behavioural observation. The amount of NNS was computed for the whole 24-h period and separately for each behavioural state (waking, quiet sleep, paradoxical sleep and ambiguous sleep). All the continuously fed infants showed a typical pattern of NNS. There were no differences in amount of NNS between continuously fed and control infants in any behavioural state. These results suggest that NS does not contribute to the long term maintenance of the NNS activity.