Objective To explore the function of trefoil factor 3(TFF3) during the self-healing of experimental gastric ulcer in rats,and to observe the changes of TFF3 in hypophysis and blood serum. Methods The expression and changes of TFF3 peptide and mRNA in hypophysis at 42 gastric ulcer，21 saline and 6 normal rats were detected by immunohistochemical SP and RT-PCR methods respectively.The content of TFF3 peptide of blood serum in different phase was detected by ELISA.In situ hibridazation method (ISH) was used to detect the location of TFF3 mRNA in hypophysis. Results TFF3 immunoreactive profiles were mainly located in some cells of adenohypophysis(AP),and neurohypophysis（NP）,but TFF3 mRNA only in some cells of AP by ISH.The average absorbance(AA) values increased from the day 1 to 6 after gastric ulcer，reached its penk on the 6th day,then a little decreased on the day 10, increased on day 14 again,then decreased on the day 23，but remained at a high level compared with the control group（EM>P /EM>0.01 orEM> P/EM> 0.05）.In NP,there was a high level undulation from day 2 to 23 with the highest on the 14th day（EM>P/EM> 0.01 or EM>P /EM>0.05）.TFF3mRNA transcription was detected in every group.The AAof TFF3/GAPDH was obviously higher in gastric ulcer group on the day 2to 23 compared with the control group（EM>P/EM> 0.01