We developed a new technique of reconstruction in Billroth 1 gastrectomy, jejunal pouch interposition (JPI). The interposed jejunal segment consists of a proximally double-plicated pouch and a distally isoperistaltic conduit. From 1987 to 1994, the JPI was performed on 102 patients with gastric carcinoma. The postoperative functional assay was carried out at least one year later after surgery. Sixty-five patients with the conventional Billroth 1 reconstruction (B-1) during the same period were employed as the control. Gastric emptying time estimated with scinti-scanning was significantly delayed in the JPI group compared with the B-1 group (p < 0.05). All individuals with JPI had meals three times a day whereas 13% of those with B-1 required those more than three times (p < 0.05). The incidence of dumping syndrome was significantly lower in the JPI group (6%) than the B-1 group (20%) (p < 0.05). The reflux of bile into the residual stomach was observed in the scintiscanning at 78% of patients with B-1 whereas 10% of those with JPI (p < 0.01). Endoscopy revealed that regurgitation gastritis was significantly decreased in the JPI group compared with that in the B-1 group (p < 0.01). These results suggest that the JPI prevents small stomach syndrome, dumping syndrome and alkaline reflux gastritis after the B-1 reconstruction.