Endoscopic and histological findings of the stomach and bile acids composition of intra-gastric bile were examined in 18 patients with bile reflex gastritis after the distal gastrectomy by the Billroth I procedure (B-I) in 10 cases and by the Billroth II (B-II) in 8 cases. Six of these patients were treated with ursodeoxycholic acid (UDCA) for at least 4 weeks, and the effects of UDCA on bile reflux gastritis were also analyzed. The endoscopic and histological findings of gastritis were more severe in patients of the B-II group than in those of the B-I group. The percentage of chenodeoxycholic acid (CDCA) in the intra-gastric bile was significantly higher in the B-II group than in the B-I group. By the treatment with UDCA, 4 out of 6 patients showed improvement of the clinical symptoms and endoscopic findings improved in all cases. With the UDCA treatment, the percentage of UDCA in intra-gastric bile increased and that of CDCA decreased significantly. These results suggest that UDCA is useful for the treatment of bile reflux gastritis after gastrectomy.