Continuous positive airway pressure (CPAP) applied by endotracheal (ET) tube in the pharynx (nasopharyngeal CPAP, n-CPAP) is widely used for the treatment of mild respiratory distress syndrome and of apnoeas of prematurity. Effects on breathing pattern and on different types of apnoeas are not fully understood. We wanted to know the effect of discontinuing n-CPAP on the respiratory rate, apnoeas and bradycardia/desaturation events. Thirteen prematurely born infants with bradycardia and/or desaturation events were studied when weaning from n-CPAP was clinically considered. Polygraphic studies were performed for 2 h during n-CPAP therapy and for 2 h without CPAP. Nasal flow was measured by registering expiratory pCO₂ at the free nostril opening. During n-CPAP, the respiratory rate was significantly lower, there were fewer obstructive apnoeas, more short central apnoeas (6–9 s) and less severe apnoea-associated desaturations. During n-CPAP, the infants spent significantly more time in a state of quiet breathing.