No consensus exists concerning the influence of head position and head position change on body posture and motility. Especially the existence of an asymmetric tonic neck reflex (ATNR) in full-term newborns is an issue of discussion. Three-hour video recordings were made of 15 full-term appropriate for gestational age (AGA) and 15 full-term small for gestational age (SGA) infants between the third and eight postnatal day. During a playback of the video recording head position, head position change and several movement patterns of the four limbs were fed into a computer using an event-detecting program. Furthermore, spontaneous head turnings were selected and body posture just before, immediately at and 1 min after the head turning were sketched. The data were analyzed concerning: (1) influence of head position on symmetry of movement of the four limbs; (2) the existence of an ATNR and ATNR-related patterns. In both AGA and SGA infants all movement patterns except hand-face and hand-mouth contact showed a symmetrical distribution, independent of head position. Furthermore, the occurrence of an ATNR following a spontaneous head turning in both AGA and SGA infants was rare. From our results it may be concluded that the ATNR is rare in full-term AGA and SGA newborns. Furthermore, this study demonstrates that head position is not a major factor influencing quantitative aspects of spontaneous motor behaviour. The results are of clinical importance as they imply that in the examination of the neurological condition of the full-term newborn infant by means of observation of spontaneous posture and motility, head position is not of major importance.