A 28-yr-old mother and her 10-year-old daughter with generalized juvenile gastrointestinal polypsis, arteriovenous (AV) malformations of the lung and severe digital clubbing are described. The AV malformations were documented by pulmonary angiography in both subjects, and generalized juvenile polyposis was confirmed histologically and radiographically. Since pulmonary AV malformations associated with juvenile polyposis has not been previously reported, a new hereditary syndrome is proposed.