Juvenile polyposis (JP) was first distinguished from other gastrointestinal polyposis syndromes in 1964. Since then, some 272 cases of this entity have been reported in the literature. The underlying polyps found in JP are of the hamartomatous type, but it is known that juvenile polyps may contain adenomatous tissue, or may be accompanied by adenomas. For the most part, juvenile polyps are found in the colon, but may also develop in the stomach, duodenum, jejunum or ileum. In 20 to 50% of the cases, juvenile polyposis occurs as a familial condition. Extra-intestinal anomalies are found in approximately 11% of JP patients. A particular clinical feature is anaemia caused by chronic gastrointestinal bleeding. In infants and young children, however, massive diarrhoea may become life-threatening. A reported malignant degeneration rate of 17.6% (among known cases) justifies the classification of JP as a precancerous condition, and has both therapeutic and, in particular, prophylactic consequences. These include the need to carry out regular follow-up examinations of the entire gastrointestinal tract, and also screening examinations in other members of the family.