This study was carried out to estimate reliability of frozen section against permanent preparation in gastric biopsies and all biopsies and all biopsies against gastrectomized specimnse. From July, 1977 to June, 1979, 667 cases were biopsied at Seoul Paik Hospital, In Je Medical College. Out of 667 cases, frozen section was performed in 575 cases in addition to permanent tissue preparation. From each biopsied material, one to four sections were made either for frozen or permanent preparations. In this series, 107 cases were gastrectomized of which 80 cases were proven to be carcinoma and 27 cases were non-malignant lesions. The correspondence of frozen section with permanent preparation of gastric biopsy was 85.7%, while 77.6% of permanent preparation of gastric biopsy corresponded with final diagnosis of gastrectomized specimens. 12 out of 107 gastrectomized patients revealed early carcinoma, of which 11 cases were detected by the biopsies, only one missed. The detect-ability will increase if endoscopist can properly select the biopsy site. The authors also wish to stress secondary benefit of making both frozen and permanent sections because of chances of studying sections at different layers of the tissue at different directious.