Recently in Japan, most of surgeons have been performing restorative proctocolectomy with ileoanal anastomosis for ulcerative colitis, leaving unsolved problems with regard to postoperative complications. Analysis was made on subtotal colectomy with colorectal anastomosis with the following policies. Firstly, the inflammation of the remnant intestine could be easily and correctly controlled by medication in outpatient. Secondly, carcinomas associated with ulcerative colitis can be discovered by postoperative colonoscopic examinations. Operations were carried out to 26 cases of ulcerative colitis for the past 13 years. Subtotal colectomy with colorectal anastomosis were performed to 11 cases. Three cases of colorectal carcinomas associated with ulcerative colitis were experienced. One of the resected specimen was investigated using stereomicroscopy after alcian blue staining to formalin fixed one. As a result of this research, we have convinced that colorectal anastomosis should be favorable surgical potion to the cases of chronic ulcerative colitis because postoperative anal function and quality of life are excellent in our series, in addition, carcinomas in the remnant intestine can be probably easily found out at the early stage by annual colonoscopic examinations with dye staining.