Two types of waterbeds were developed to impart compensatory vestibular-proprioceptive stimulation to premature infants. Infants (21) ranging in gestational age from 27-34 wk and birthweights from 1050-1920 gm were included in this pilot study. Assignment to experimental and control groups was made by random design. The experimental group consisted of 10 infants who were placed on a gently oscillating waterbed before the 6th postnatal day, where they remained for 7 days. Their clinical progress was compared with that of a control group of 11 similar babies. Waterbed flotation was a safe procedure; there were no significant effects on the infants'' vital signs, weight or frequency of emesis. Highly significant differences were found in the incidence of apnea between the 2 groups, with infants on the oscillating waterbed having significantly fewer apneic spells. Infants placed on the waterbed during the 1st 4 postnatal days benefited more than those placed later. A non-oscillating waterbed was found clinically useful for very small prematures with severe skin problems, for infants recovering from abdominal surgery and for infants receiving parenteral nutrition.