AIM: To study the protective effect of Gan_wei_ning (GWN) on gastric mucosa. METHODS: Rat experiment: 35 rats were randomly divided into A) saline, B) absolute EtOH, and C) GWN+EtOH. All rats were fasted for 24 h and deprivated of water for 2 h before the experiment. 1 mL of saline was given to Group A and Group B and 1 mL of oral solution of GWN to Group C. After 2 h, 1 mL of 0.9% sodium chloride was given to Group A and 1 mL of EtOH was given to Group B and C. Two hours later, their stomachs were taken out and the gastric mucosa was observed by macroscopy, optical microscope and electron microscope, and Na +_K +_ATPase of gastric mucosa, homogenate, gastric acid, endothelin (ET) and 6_keto prostaglandin F 1α in serum were determined. Clinical study: Patients with gastritis were treated with GWN 20 g, po, tid×8 wk. RESULTS: GWN enhanced the activity of Na +_K +_ATPase, increased PG level, and reduced ET level in serum, but did not affect the secretion of gastric acid. The gastric mucosal injury in Group C was obviously milder than that in Group A. CONCLUSION: GWN has protective effect on gastric mucosa.