The closure of the vocal folds during swallowing is known to contribute to airway protection along with epiglottic inversion and closure of the false vocal folds. It is therefore plausible to expect that unilateral vocal fold impairment without complete closure might increase the likelihood of aspiration. The authors of this paper investigated the swallowing pathophysiology of individuals with unilateral vocal fold immobility (UVFI) to determine factors that best predicted aspirators from non-aspirators. They analysed quantitative swallowing measures from modified barium swallow procedures undertaken on all patients with a UVFI over a five-year period at their institution. Data was obtained from 61 eligible patients, with an average age of 62 (range 23-90); 52% were female. Almost 60% had a left-sided UVFI, with 23% demonstrating aspiration as indicated by a PAS score above five (Rosenbek penetration-aspiration scale, PAS). The broad aetiologic categories for UVFI were: central nervous system, skull base tumour, iatrogenic, peripheral tumour and idiopathic causes. The most common pathophysiology seen (68%) was delayed airway closure, regardless of aetiology. However, this feature occurred with similar frequency in aspirators and non-aspirators. Reduced pharyngeal constriction on the other hand occurred in significantly more aspirators (79%) than non-aspirators (34%) p=0.003. Thus, the majority of aspiration occurred before closure of the larynx (due to delayed closure/premature bolus spill) and after the swallow due to poor pharyngeal constriction and aspiration of residue. Only 3/14 cases aspirated during airway closure, and this may be directly attributed to the UVFI. The authors acknowledge the limitations of this retrospective review. Nevertheless, the results spark interesting questions for further research.