In the past 35 years, we have experienced 355 cases of HTPS, and about half of them, GER was found simultaneously by upper G.I. series. In the present study, in order to clarify the interrelationship between HTPS and GER, measurements of LESP including its gastrin response were done by open tip method. Control patients were consisted of 10 infants who had neither HTPS nor GER. THE following results were obtained. 1) GER(+) group; 6 cases were studied. The free and gastrin responces of LESP were lower than the control. But they increased markedly after pyloromyotomy. 2) GER(-) group; 10 cases were studied. There was no difference in free LESP, but the response to gastrin was lower than the control. However, it become to normal range after the opration.
