• Infants born to opiate-abusing mothers have a decreased ventilatory response to carbon dioxide and a five to ten times increased risk of sudden infant death syndrome (SIDS). These abnormalities of ventilatory control may be associated with abnormal sleeping ventilatory patterns. Therefore, 28 overnight pneumograms (respiratory pattern recording and electrocardiogram) were obtained from 27 infants of substance-abusing mothers (ISAM) (five opiate, seven phencyclidine hydrochloride, three cocaine, and 12 polydrug abusers) and compared with pneumograms from 43 control infants. Pneumograms were quantitated for total sleep time, greatest duration of apnea, total duration of apnea greater than or equal to 6 s, periodic breathing, and mean heart and respiratory rates. The ISAM had a longer total sleep time, greater durations of apnea, a higher total duration of apneas greater than or equal to 6 s, more periodic breathing, a higher mean respiratory rate, and a lower mean heart rate. Thirty-two percent of pneumograms from ISAM were abnormal compared with 9.3% of the control pneumograms. We conclude that ISAM have abnormal sleeping ventilatory patterns that may be related to their increased SIDS risk.