PURPOSE: The purpose of this study is to describe the rib changes seen in patients with bronchopulmonary dysplasia (BPD). MATERIALS AND METHODS: Serial chest radiographs of nine premature infants with BPD who showed diffuse rib enlargement were reviewed for hyperinflation, which was compared with the observed degree of rib enlargement. Vibrator chest physiotherapy was performed in all cases, and five infants underwent conventional ventilation plus high frequency oscillatory ventilation therapy. Their calcium level was normal where-as alkaline phosphatase and phosphate levels were high. In all infants except one, liver enzyme levels were normal. For the treatment of patent ductus arteriosus, infection, and BPD, medications including indomethacin, antibiotics, and examethasone were administered. Vitamin D was given to all patients with total parenteral nutrition. RESULTS: Rib enlargement was found to be severe (n=4), moderate (n=3), or mild (n=2) with undulating margins or posterior tapering (n=2). Hyperinflation was noted in eight patients, in seven of whom it was moderate to seve r e. Among these seven, rib enlargement was severe (n=2), moderate (n=3), or mild (n=2). In one infant with mild hyperinflation, rib enlargement was seve r e. Bilateral irregular infiltrates and at-electases were noted in all patients. CONCLUSION: In BPD patients, rib enlargement may be seen. In order to differentiate this process from systemic bone disease or bony dysplasia, an awareness of the rib changes occurring in patients with BPD may be important.