To describe mortality and neurodevelopmental outcome before and after the introduction of rescue therapy with natural surfactant in two neonatal units in Toronto, Canada, a retrospective cohort study of 891 liveborn 23-26 wk gestational age infants, 421 presurfactant (1982-1987) and 470 postsurfactant (1990-1994) was performed. Overall mortality was stable over time (41% vs 35%, p = 0.077), but declined for inborn 24 (71% vs 43%, p = 0.03) and 26 wk (26% vs 13%, p = 0.01) gestational age infants and was higher in surfactant-treated infants (p < 0.0001). Chronic lung disease (61% vs 34%, p < 0.0001) and bilateral blindness (8% vs 4%, p = 0.004) declined over time, with stable rates of cerebral palsy (12% vs 15%), cognitive deficit (27% vs 26%) and aided sensorineural hearing loss (5% vs 4%). Sixty-five percent of surviving infants in both eras were free from neurodevelopmental impairment, and severe impairment declined over time (p = 0.035). This study shows no secular change in overall mortality in a large cohort of 23-26 wk gestational age infants since the introduction of rescue therapy with natural surfactant. However, it does suggest that maternal transfer to and delivery of all extremely preterm infants in high risk perinatal centres is justified.