This report describes a syndrome of delayed respiratory distress occurring in premature infants usually under 1,250 gm at birth. Unlike hyaline membrane disease, this syndrome occurs after four to seven days in a previously healthy infant; also unlike hyaline membrane disease, it persists for two to four weeks. Chronic pulmonary insufficiency of prematurity (CPIP) carries a 10% to 20% mortality rate. The infants are frequently apneic, require supplemental oxygen, but lack the radiologic findings of hyaline membrane disease or bronchopulmonary dysplasia. When compared with nondistressed infants of similar birthweight, infants with CPIP demonstrate slowly progressive atelectasis, hypoxemia, and hypercapnia. Recovery is usually complete by 60 days of age. The importance of CPIP is that an awareness of its existence can eliminate a false sense of security, often communicated to anxious parents, during the four-to-seven-day grace period before its appearance is clinically obvious. The physiologic similarities between CPIP and hyaline membrane disease suggest that lack of surfactant may play a role in the pathogenesis of CPIP.