OBJECTIVE To determine the relationship between decision to delivery interval and perinatal outcome in severe placental abruption. DESIGN A case-control study. SETTING Large inner city teaching hospital. METHODS Retrospective case note review of pregnancies terminated following severe placental aburption and fetal bradycardia. One year paediatric follow up by case note review or postal questionnaire. The differences in outcome (death or cerebral palsy) were examined using non-parametric and univariate analysis for the following time periods--times from onset of symptoms to delivery, onset of symptoms to admission, admission to delivery, onset bradycardia to delivery and decision to delivery interval. MAIN OUTCOME MEASURES Prenatal death or survival with cerebral palsy. RESULTS Thirty-three women with singleton pregnancies over 28 weeks of gestation, admitted with clinically overt placental abruption, where delivery was effected for fetal bradycardia. Eleven of the pregnancies had a poor outcome (cases), eight infants died and three surviving infants have cerebral palsy. Twenty-two pregnancies had a good outcome (controls): survival with no developmental delay. No statistically significant relationship was found between maternal age, parity, gestation, or birthweight and a poor outcome. A statistically significant relationship between time from decision to delivery was identified (P = 0.02, Mann-Whitney U test). The results of a univariate logistic regression for this variable suggest that the odds ratio of a poor outcome for delivery at 20 minutes compared with 30 minutes is 0.44 (95% CI 0.22-0.86). Fifty-five percent of infants were delivered within 20 minutes of the decision to deliver. Serious maternal morbidity was rare. CONCLUSION In this small study of severe placental abruption complicated by fetal bradycardia, a decision to delivery interval of 20 minutes or less was associated with substantially reduced neonatal morbidity and mortality.