Vocal fold paralysis accounts for 10% of the larynx congenital abnormality, being the second most common cause of laryngeal stridor in childhood. As to unilateral vocal fold paralysis, the main cause is left-sided iatrogenic injury to the recurrent laryngeal nerve, secondary to surgery to correct the patent ductus arteriosus. In this study we reviewed the literature, reporting a case of a child who, after having undergone surgery to close the patent ductus arteriosus, evolved with breathing difficulty and dysphonia. We suggest that flexible fiberoptic laryngoscopy is carried out pre-and post surgery in children for whom heart surgery to correct congenital abnormalities is indicated, thus allowing for early diagnosis of vocal fold paralysis and the selection of the best management approach.Rev Bras Otorrinolaringol. V.71, n.3, 382-5, may/jun. 2005