Trichuriasis is a human intestinal infection caused by Trichuris trichiura, most commonly known as whipworm. It is characterized by the invasion of the colonic mucosa by the adult worm of the nematode. This infection usually causes no clinical symptoms, although a severe infection can cause abdominal pain, rectal prolapse, anemia, anorexia and bloody diarrhea. The diagnosis is made by identification of eggs or worms in feces. Several reports have described the detection of T. trichiura during colonoscopy. To our knowledge, this is the first report of a case of T. trichiura diagnosed by colonoscopy in Buenos Aires province, Argentina