A father and his daughter, both suffering from the Gardner syndrome, came to our attention at the same time with symptoms produced by primary carcinoma of the duodenum. Duodenal polyps were also present. Studies of these and other patients with similar features strongly suggest that these lesions may be a part of this inherited condition. Roentgenographic examination of the upper portion of the gastrointestinal tract should be a routine part of the follow-up of patients with this syndrome.