The purpose of this study was to determine the effectiveness of a water-pillow treatment in reducing bilateral head flattening of preterm infants. The subjects were 21 healthy infants of less than 36 weeks gestational+ age. Care of the experimental babies included supporting the head on a small water pillow and supporting the torso at the same level to avoid flexion or curvature of the spine; the control group received customary care. The ratios of the anterior-posterior diameter to the biparietal diameter were significantly different for the two groups (p less than .0005). The heads of the control infants became flattened on both sides, while those of the experimental babies maintained the round shape they had at admission to the unit. The findings support the use of a small water pillow, in combination with support for the torso, as a means of alleviating bilateral head flattening in preterm infants.