Surfactant protein‐A (SP‐A) was measured in bronchoalveolar lavage (BAL) samples from ventilated neonates in order to study the concentration of SP‐A with regard to: 1) high‐frequency oscillatory ventilation (HFOV) vs. conventional mechanical ventilation (CMV); 2) the postnatal course and ontogeny of SP‐A; and 3) the correlation with measurements of pulmonary function. Patients on HFOV had markedly lower BAL SP‐A concentrations on days 1 and 2 compared to those on CMV, which may indicate influence of mode of ventilation on surfactant metabolism. The SP‐A concentrations increased postnatally concurrent with resolution of acute respiratory distress syndrome. Finally, there were only weak correlations between BAL SP‐A concentration and dynamic lung compliance and oxygen requirement. Pediatr Pulmonal 1990; 9:166–169.