This study was carried out to assess the effects of bombesin on the gastric secreticn of perfused rat stomach with administered by subcutcneous injecticn. The results were obtained as follows. The bombesin group did not produce a significant change in the volume of gastric juice compared with that of control group. The bombesin plus pentagastrin group showed a significant increase of volume compared with tbat of ccr,trcl group. 2) The hombesin group did nct- produce a significant change in the titratable aid output of gastrc juice compared with that of control group. The titratable acid output caused by bombesin plus pentagastrin was significant increase than that of control group, but significant decrease of titratable acid output at 60,70 minutes after injection comparecd With that of pentagastrin group.