The authors present the case of a 17-year-old girl with tuberous sclerosis (TS) who presented with symptoms of intussusception. Although endoscopically diagnosed with multiple colonic polyps, presumed to be hamartomas, and an invasive rectal adenocarcinoma, postoperative pathology findings confirmed the rectal cancer and showed multiple colonic adenomas. Multiple colonic adenomatous polyps in a young girl with tuberous sclerosis is extremely rare. Furthermore, we believe that this is the first report of an invasive adenocarcinoma of the large intestine occurring in a patient with TS.