We experienced a case of colonic cancer complicating with ulcerative colitis which had a 19-year history in a 50-year-old woman. Nineteen years before (1973) when the patient was 32 years old, she was seen at the hospital because of mucobloody stool and was diagnosed as total ulcerative colitis. The patient had been treated for the disease until 50 years of age (1992) when she was admitted to the department because of left-sided abdominal pain and constipation. Barium enema and colonoscopy revealed the stricture of the lumen of the transverse colon and biopsy specimens were diagnosed as poorly differentiated adenocarcinoma. Laparotomy revealed diffuse dissemination of the cancer in the abdominal cavity and a non-curative left-sided colectomy was performed. Nine months later the patient died of peritonitis cartinomatosa in spite of cancer chemotherapy. In the clinical course of this patient mild dysplasia was detected in May 1988 by endoscopic surveillance, but in December 1988 and August 1991, dysplasia was not detected. These facts make us reconsider the way of treatment of the patient with dysplasia. Reported cases of cancer of the colon associated with ulcerative colitis in Japan have been relatively rare compared with those in the United States. We could collect 182 cases from the published papers and abstracts in the proceedings until December 1995. These cases are also reviewed here.