【Purpose】 Nasogastric tube feeding is a well-known cause of aspiration pneumonia．It has been reported that pneumonia associated with the tube is induced by aspiration of gastroesophageal reflux． However，not all patients who developed pneumonia exhibited reflux．These facts indicate that other factors also contribute to inducing pneumonia．The tube irritates the site of swallowing provocation，therefore it is hypothesized that tube placement might affect swallowing reflex and promote aspiration of saliva．In this study，we prospectively investigated the frequency of swallowing events during wearing of a nasogastric tube in order to clarify the effect of tube placement on the reflexive swallow．

【Method】 The study population consisted of five normal subjects．The subjects were instructed to rest and thereafter a feeding tube with an 8 French bore was inserted．Swallowing events were counted for 15 minutes before insertion of the tube and for 60 minutes after the insertion．Swallowing was identified by submental electromyographic activity and visual observation of laryngeal movement．

【Result】 The frequency of swallowing per five minutes immediately after insertion of the tube (19-29 times) was higher than that before the insertion (8-18 times) (Mann-Whitney test，p＜0.01)．Subsequently，the frequency of swallowing tended to decrease．Forty minutes after the insertion，the frequency was lower (1-15 times) than that before the insertion (p＜0.05)．

【Conclusion】 These results suggest that placement of a nasogastric feeding tube affects reflexive swallowing．