Premature infants requiring an ophthalmic examination or even surgery for retinopathy of prematurity (ROP) have a high prevalence of co-existing bronchopulmonary dysplasia (BPD). Reactive airway is one of the clinical presentations of BPD. We report two cases of bronchoconstriction following instillation of mydriatic eye drops. One occurred during induction of anesthesia for laser photocoagulation and the other before screening of ROP. The most likely cause in each case was phenylephrine eye drops. We recommend that the minimal dosage of phenylephrine needed to attain proper mydriasis should be instilled to infant patients, and the possibility of bronchoconstriction occurrence kept in mind, especially for infants with low body weight with BPD.