Background: there is limited data regarding the clinical characteristics and outcome of the neonate requiring ventilatory assistance who develops persistent bradycardia (PB) requiring cardiopulmonary resuscitation (CPR). Objectives: (1) to determine the percentage of newborn infants requiring respiratory assistance who develop PB and require CPR as part of resuscitation; (2) the associated clinical events; and (3) the short term outcome. Methods: the medical charts of infants admitted to a neonatal intensive care unit who developed PB, defined as a heart rate < 80 beats/min requiring CPR, were retrospectively reviewed. Results. for 3 years, 39 (2.6%) of 1485 infants exhibited 62 episodes of PB requiring CPR; this represents 5.6% of 695 intubated infants. Fourteen (36%) infants rapidly responded to chest compressions only with restoration of heart rate within 2 min; termed brief CPR. None died in-hospital. Twenty-five (64%) infants required prolonged chest compressions, i.e. > 2 min (termed prolonged CPR); 21 also received epinephrine. The median postnatal age at onset of CPR was 20 days (range 1-148 days) and the duration of CPR was 10 min (range 3-73 min). The more common medical conditions that may have contributed to the PB included severe bronchospasm associated with chronic lung disease (CLD) (n = 6), shock associated with sepsis (n = 4) and necrotizing enterocolitis (NEC) (n = 2), pneumothorax (n = 2), inadequate or improper ventilation (n = 3), other (n = 8). Nineteen (76%) infants died: 13 within 24 h of the event and six from 3 to 194 days following CPR. At 18 months follow-up, four of the six infants evaluated have a moderate to severe neurodevelopmental deficit. Of the nine infants requiring brief CPR who were evaluated, five are developing normally and four have a moderate to severe neurodevelopmental deficit. Conclusion: CPR in the neonate who requires ventilatory assistance is not uncommon. When brief in nature, mortality is low and short-term outcome is likely to be determined by the underlying medical condition. When CPR is prolonged, mortality is high and short-term outcome is poor. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.