We surveyed outcome in 1095 (95.5%) of 1147 very-low-birth-weight infants born in North Carolina in 1984 to determine the incidence of chronic lung disease (CLD) and to learn whether there are differences in incidence among newborn intensive care units (NICUs). At 30 days of age, 39% of surviving infants who had received mechanical ventilation for more than 48 hours were still respirator dependent; 15% were only oxygen dependent. By 3 months, the rates had fallen to 8% and 7%, respectively. By 6 months of age, only 1.6% were respirator dependent but 3% were oxygen dependent and 9% had died. The NICUs differed widely in incidence of CLD, without relation to number of very-low-birth-weight infants treated or to whether treatment was by pediatric residents. Rates of CLD among survivors at 30 days were not inversely related to prior mortality rates. Incidence varied inversely by birth weight, but differences among NICUs were only partly due to differing weight distributions.