Four-hour recordings of heart rate and respiration during spontaneous sleep and wakefulness were obtained from 17 cocaine-exposed and 14 control infants at 2 weeks of age. The median values for heart and respiratory rate and variability were determined for each 1-min epoch of quiet and active sleep. Overall mean rates and variabilities were determined for each state. The cocaine-exposed infants showed significantly greater sleep state effects on heart rate relative to the control infants. Recency of cocaine exposure was not a factor in the differences; even those cocaine-exposed infants who tested negative for the drug perinatally differed significantly from those who had never been exposed. Heart rate variability was increased in cocaine-exposed infants relative to controls in both sleep states. Respiratory rate and variability were not significantly different in the cocaine-exposed and control infants. These results suggest differences in cardiovascular control in infants of cocaine-abusing mothers compared to infants without cocaine exposure. The mechanism responsible for these differences is unclear and may reflect cocaine-induced changes in the autonomic physiology of developing infants or some indirect effect of maternal cocaine use.