Objective. To study the effect of exogenous bovine surfactant on oxygen and ventilatory requirements in neonates with respiratory deterioration due to pulmonary hemorrhage. Design. Retrospective case series. Setting. Three regional neonatal intensive care units. Methods. Infants who received surfactant following a clinically significant pulmonary hemorrhage during the time period July 1991 to December 1993 were identified from a database. Infants were excluded if any other cause was found to explain their deterioration. The primary outcome was change in respiratory status following surfactant therapy, as reflected by oxygenation index (OI) and arterial/Alveolar oxygen ratio. Data points were taken as averages of 3 through 6 hours and 0 through 3 hours for the 6 hours before and after surfactant. Differences were analyzed using analysis of variance for repeated measures, with treatment and time as co-variates. Results. Fifteen patients fulfilled inclusion criteria. Median values (range): birth weight, 960 g (595 to 4045); age at pulmonary hemorrhage, 24.4 hours (0.3 to 62); and interval between pulmonary hemorrhage and surfactant therapy, 10 hours (3.7 to 46.5). Mean OI improved from 24.6, at 0 to 3 hours presurfactant, to 8.6 at 3 to 6 hours postsurfactant (P .001). No patient deteriorated following surfactant therapy. The primary respiratory diagnosis was respiratory distress syndrome (RDS) in 8, meconium aspiration syndrome in 3, and isolated pulmonary hemorrhage in 4. All those with RDS had also received surfactant before their pulmonary hemorrhage. Conclusions. Exogenous surfactant appears to be useful adjunctive therapy in neonates with a clinically significant pulmonary hemorrhage. Its use for this indication should be further investigated by a randomized controlled trial.