Eight ventilator-dependent infants with bronchopulmonary dysplasia (BPD) were treated with dexamethasone (0.5 mg/kg/day). Therapy was initiated at 19.3 +/- 3.9 days of age, continued at the initial dose for 7 days, then tapered over 2 weeks. The clinical course of these infants with BPD was compared to that of 8 similar ventilator-dependent infants with uncomplicated hyaline membrane disease (HMD). At study entry, the BPD patients had significantly higher ventilator rates, peak inspiratory pressures, mean airway pressures, alveolar-arterial oxygen gradients and fraction of inspired oxygen (FiO2) values. After 7 days of dexamethasone therapy, ventilator rates, peak inspiratory pressures, mean airway pressures, FiO2 values and alveolar-arterial oxygen gradients improved significantly. At this time, ventilator rates, peak inspiratory pressures and FiO2 values were similar to those of patients with uncomplicated HMD. BPD patients were extubated after 6.5 +/- 2.4 days of therapy. The incidences of septicemia, rickets and retinopathy of prematurity were similar in the BPD and uncomplicated HMD patients. Most dexamethasone-treated patients developed arterial hypertension during the first 48 h of therapy. Blood pressures returned to normal within 7 days of stopping therapy. All BPD patients had cosyntropin responses tested 5.5 +/- 2.6 weeks after stopping therapy. Six were normal. Two had inadequate responses. At 1 year adjusted age, the dexamethasone-treated BPD infants and HMD infants had similar radiographic bone ages, similar growth patterns and similar scores on the Bayley infant development scale. Dexamethasone was useful in the treatment of early BPD. Used as short-term therapy, the drug had minimal complications and no long-term sequelae.