Abstract Juvenile polyposis is an uncommon condition characterized by the development of multiple juvenile polyps, predominantly in the colon but also in the rest of the gastrointestinal tract. The condition usually presents in childhood; only 15 per cent of patients present as adults. The rarer and often fatal form, namely, juvenile polyposis of infancy, is typified by diarrhoea, protein-losing enteropathy, bleeding and rectal prolapse. The more common form of juvenile polyposis (affecting the colon, stomach and small bowel) occurs in the first or second decade with rectal bleeding and anaemia. A family history of the condition is found in 20–50 per cent of patients with apparently an autosomal dominant trait. The gene for juvenile polyposis has not yet been identified. Epithelial dysplasia is common and the cumulative risk of colorectal cancer is > 50 per cent. Various extracolonic abnormalities may also occur. Most patients are treated surgically for colonic polyps, although endoscopic polypectomy is also an option. The rest of the gastrointestinal tract should be screened as should asymptomatic first-degree relatives.