Narcotic antagonists are generally administered to newborns only if they exhibit evidence of cardiorespiratory depression in the delivery room following maternal narcotic analgesia. To investigate the presence of subtle narcotic depression, we have evaluated the effects of naloxone vs placebo in a double blind parallel group study in 43 normal term newborns whose mothers had received routine narcotic analgesia within 6 hrs prior to delivery. The infants were given an IM injection of 20 μg/kg naloxone after the 1 min Apgar, and the following parameters were compared: Apgar scores at 1 and 5 min., capillary blood gases at 1, 30, 60, 120, and 240 min., and Scanlon neurobehavioral assessments at 1, 4, and 24 hrs. No adverse effects were observed. Neither the Apgar scores nor the blood gases differed significantly between the two groups. The alertness score was significantly higher for the naloxone group at 1 and 4 hrs (p < .05, .05). The general score for the Narcan group was higher at 4 hr (p < .05) and 24 hrs (p < .055). Response to sound was significantly higher in the naloxone group at 24 hrs (p < .05). These data suggeat that maternal narcotic analgesia may produce subtle changes in alertness and general behavior not reflected by Apgar scores or respiratory status. It may be advisable, therefore, to administer naloxone to most infants on a routine basis if birth is within 6 hrs of maternal narcotic administration.