The identification of cellular deficiences in the ability to repair damage in DNA in individuals with several cancer‐prone genetic disorders, has led to the idea that defective DNA repair results in cancer. In patients with trichothiodystrophy, however, a recently discovered defect in the repair of ultraviolet damage in DNA is not associated with cancer‐proneness. Thus our previous ideas about the connections between DNA repair capacity and cancer susceptibility need to be reevaluated.