Background The role of pharyngeal impedance recording for assessing pharyngeal function is yet to be established. The aim of this study was to evaluate impedance flow interval, a novel parameter, in relation to bolus residue and the occurrence of aspiration. The effect of catheter configuration was also assessed. Methods We studied 12 children (1.8-13.5years) with cerebral palsy, who were all referred for a videofluoroscopy due to suspected aspiration risk. Pharyngeal impedance patterns during bolus swallowing were recorded simultaneously with fluoroscopy. Two different catheter configurations were used: Catheter 1, 1.9mm diameter with 1cm electrodes and Catheter 2, 3.2mm diameter with 2cm electrodes. The flow interval was based on the objective assessment of impedance drop and recovery across multiple impedance segments and was correlated with fluoroscopic evidence of postswallow bolus residue and deglutitive aspiration. Key Results One hundred and thirty two liquid swallows were evaluated. Patient swallows with aspiration compared to those without aspiration had a longer flow interval (Cath 1 P=0.005; Cath 2 P<0.001). Patient swallows with residue had a longer flow interval, however this was only significant for swallows recorded using Catheter 2 (P=0.004). Multiple logistic regressions showed that higher flow interval was a better marker of the presence of aspiration [odds ratio (OR) 13.4 (3.0, 59.2); P<0.001] than the presence of residue [OR 3.8 (1.4, 10.3); P=0.01]. Conclusions andInferences We present novel findings suggesting that impedance measurement can detect alterations in flow characteristics of pharyngeal swallow that have the potential to predict to deglutitive aspiration risk.