A typical case of dyskeratosis congenita (DC) is presented with its classic triad of poikiloderma, ungual dystrophy, and leukoplakial changes of the mucosal surfaces. The extensive involvement of the mucous membranes of the bronchial and gastrointestinal tracts is emphasized. For the first time, to our knowledge, chromosomal changes consisting of an increase in structural and numerical abnormalities are mentioned. Finally, some comments are made concerning the association of this disease with immunologic abnormalities, dysplasia of the reticulolymphoid and hematologic systems.