This review provides the readers with background information on the state of the art and science of inhaled nitric oxide (iNO) as therapy for prevention or amelioration of bronchopulmonary dysplasia (BPD) in preterm infants. The goal is to review and critique relevant published information. A total of six clinical trials, all placebo-controlled, four out of six blinded, four out of six multi-centered with a predetermined outcome of reduction in death or BPD, have been reported in full text. These definitive studies have included a total of > 2100 preterm, mostly very preterm, infants. Their designs were informed by results of earlier non-definitive studies which cumulatively enrolled > 350 preterm patients. This very substantial experience provides a firm framework for asserting that iNO will be useful in this population of patients. The use of iNO can reduce the occurrence of BPD and possibly the severity of the disorder. Optimal time of initiation, dosing (both initial dose, duration of treatment and possibly the route of administration) and most importantly, optimal patient subset selection, are not determined. Any clear adverse neurological finding in iNO-treated infants will of course limit or halt the use of this promising therapy.