Gardner's syndrome, completely expressed, consists of a triad of symptoms: polyposis of the colon, osteomatosis and mesenchymal tumours of the skin. Inheritence is autosomal dominant. In a follow-up examination amongst eleven patients with polyposis intestinalis a typical constellation of symptoms of Gardner's syndrome was found in eight. With increasing age of the patients polyposis of the colon shows a marked tendency to malignant degeneration. Because osseous lesions and striking skin pigmentation in the facial and jaw region precede polyposis coli, dentists may have an important role to play in the early detection of Gardner's syndrom. The disease is illustrated by a case report.