Maternal smoking is a risk factor for the sudden infant death syndrome (SIDS). We hypothesized that pre-natal exposure to nicotine would result in abnormalities of ventilatory activity in newborns. Neonatal rats which had been exposed to nicotine had significantly lower minute ventilation breathing air and hypoxic gas mixtures than did control animals. In both groups, anoxia elicited gasping which was equally effective in restoring eupnea. Maternal exposure to nicotine may result in a reduced metabolic rate and/or chronic hypoventilation in the newborn.