Based upon the 8 years' experience in vertical banded gastroplasty (VBG) for the treatment of morbid obesity in our department, we analysed the clinical results after operation. As a result, the weight-reducing effect and safety of VBG were found favourvable, but some of complications developed in a few, causing serious conditions. Therefore, a modification of VBG was tried in order to utilize the characteristics of VBG and to lessen the factors of complications development as much as possible. Its essential points are to utilize the His-angle by making an oblique staple line instead of a vertical one, and to block the stomach with GIA90 and EEA28 and embed the staple line by suturing the serous membrane. Because the stomach is formed into a K-shape, it has been named k-gastroplasty. Its operative mode is discussed.