Inflammation is a significant component of both clinical and experimental model BPD and is the subject of numerous basic science investigations begun since the empiric observation that BPD responds favorably to systemic steroids. The known side effects of systemic steroids have led to their cautious sequential controlled clinical investigation, initially for late treatment (at more than 30 days of age), then early treatment (two weeks), then very early treatment (seven days), and even prophylaxis (day one). The prophylactic clinical trial of inhaled steroids, starting at day three for 21 days, is a logical next step in this sequence of determining the least dangerous, yet effective means to prevent or treat the inflammatory components of BPD.