• From Jan 1, 1977, to Jan 1, 1987, verylow-birth-weight (VLBW) infants consumed almost 90% of total patient-days of assisted ventilation of all infants born in one tertiary perinatal center. In the latter five years compared with the first five years, increasing resources allowed proportionately more VLBW infants to be offered assisted ventilation, and the patient-days of assisted ventilation consumed per live birth rose by almost 60%. All VLBW infants did not benefit equally from the increased assisted ventilation. Mortality in infants with birth weights below 1200 g decreased; unexpectedly, mortality in larger VLBW infants (birth weights, 1200 g to 1499 g) rose (relative odds, 3.11; 95% confidence intervals, 1.21 to 7.99). Despite the increased consumption of ventilator resources, there was no substantial impact on overall mortality in VLBW infants.