One year's experience with MAS in a neonatal intensive-care unit is analyzed with follow-up information. Seventeen pationts or 3.7 per cent of all admissions had MAS. Four patients (23.5 per cent) died of acute respiratory failure. Two patients with MAS and persistence of the fetal circulation required cardiac catheterization to exclude cyanotic congenital heart disease. No survivors had persistent chronic lung disease. However, two of three patients with MAS and seizures had significant psychomotor retardation at follow-up examination.