Excessive enterogastric reflux following partial gastrectomy is believed to be responsible for the cause of inflammation in the gastric remnant. We examined the effect of FUT-187, a synthetic serine protease inhibitor, on symptoms and endoscopic findings in 33 patients who were diagnosed endoscopically as postgastrectomy gastritis. Patients took 50 mg FUT-187 orally after each meal and at bedtime for 8 weeks. Before treatment, 30 patients (91%) suffered from several symptoms including regurgitation and/or bitter taste in the mouth (49%), epigastric pain (42%) and nausea (36%). From endoscopic observation, erythema was detected in 32 patients, edema in 23 patients and erosion and/or ulcer in 9 patients. After treatment the global improvement rating for subjective symptoms was 76.7% (23/30) and the improvement of endoscopic findings was 63.6% (21/33). Diarrhea was observed in one patient but could be easily controlled by discontinuation of the drug. Our results suggest that FUT-187 can be a useful drug for the treatment of postgastrectomy gastritis with its efficacy and safety.