Seventeen cases of unilateral or bilateral vocal fold paralysis were diagnosed in infants younger than 12 months from 1991 to 1994 at the University of Iowa Hospitals and Clinics. Eight (47%) children with left vocal fold paralysis had a history of prior thoracic surgery--two to repair complex congenital anomalies and six to ligate a patent ductus arteriosus. During the study period, a total of 81 patent ductus arteriosus ligations were performed, yielding a 7.4% postoperative incidence of vocal fold paralysis. Seven (41%) children had idiopathic vocal fold paralysis (3 right, 1 left, 3 bilateral). Two (12%) children had VFP caused by central nervous system pathology (1 right, 1 bilateral). Tracheotomy was not required in any case. Prognosis for vocal fold paralysis varied with cause. With left vocal fold paralysis caused by thoracic surgery, no improvement was noted after an average follow-up of 6 months; with idiopathic vocal fold paralysis infants improved within an average of 6 weeks of diagnosis; with vocal fold paralysis caused by central nervous system pathology, treatment of the underlying condition was followed by return of vocal cord function. Irrespective of cause, the morbidity associated with vocal fold paralysis is minimal. Although tracheotomy is not required, careful airway observation is important. Differences and similarities of these results with other studies are discussed.