OBJECTIVE: To investigate the effects of both water volume and position changes of head and neck on swallowing using electrophysiologic study. METHOD: Twenty healthy adult volunteers (male 10, female 10) participated in this study. The oropharyngeal swallowing was investigated using electrophysiologic method of Ertekin's. Simultaneous recording of surface electromyographic potentials at submental muscles and laryngeal movement using piezoelectric sensor was performed during swallowing. The 2, 5, and 10 cc of water at 90-degree upright and 30-degree flexed head positions were used for evaluation. We recorded five parameters; swallowing reflex time, total duration, amplitude and rise time of SM musclecontraction, and laryngeal relocation time. RESULTS: The mean swallowing reflex time of 2 cc water at upright and flexed neck positions were 489+/-86.7, 462.1+/-70.7 msec, respectively. There were no significant differences in swallowing reflex time, total duration, amplitude and rise time of submental muscle contraction, and laryngeal relocation time among various conditions (p>0.05). Only amplitude of submental muscle was lower in female than male subjects regardless of volume and neck position (p<0.05). CONCLUSION: The water volume and position changes of head and neck did not influence on electrophysiologic parameters of swallowing in healthy adults.