The supine posture of 15 low-risk preterm infants was studied to establish whether they have a preferred posture and, if so, whether it changes with age. No over-all preferred posture was found. Almost always one posture was adopted most frequently, but often a great variety of other postures were adopted almost as frequently. There was no correlation between postmenstrual age and preferred posture, the number of different postures, or the duration of longest uninterrupted posture.