The effect of pediatricians' counseling to parents on infant restraint use was studied. The study population consisted of 269 women who gave birth to infants consecutively in Pittsburgh hospitals and requested that their infants be cared for by three pediatricians in a group practice. An experimental group received education regarding crash protection of infants traveling in cars during their postpartum stay and at their infants' 1 and 2 months of age well-child visits. Educational inputs included: discussions by the pediatricians on how to protect infants in cars, a pamphlet on car safety, a formal prescription for a restraint, and an actual demonstration by pediatricians of correct use of an infant restraint. A comparison group was not provided such education. Evaluation was based on actual observations of how infants were traveling in cars when they arrived at the pediatricians' office for well-child care at 1, 2, 4, and 15 months of age. Use of restraints anchored by car seat belts in the experimental group was higher than in the comparison group at each observation point by 23% at 1 month, 72% at 2 months, 9% at 4 months, and 12% at 15 months of age. The results indicated that pediatricians can be effective in increasing the protection of infants in cars, at least at the age (2 to 3 months) when the car-occupant death is especially great, but in this study the effect of their education was largely diminished by four months. Pediatricians should routinely educate their patients about crash protection of infants, but further studies are needed to determine techniques that can be used to maximize the magnitude and duration of positive effects. Additional techniques to increase the crash protection of infants, such as improved interior compartment designs and air bags, are also necessary and should be encouraged by pediatricians and other physicians.