We report a patient with Fanconi's anaemia and multiple lesions of vulvo-anal Bowen's disease. She was thrombocytopenic and lymphopenic, and NK-mediated cytotoxicity was undetectable. The vulvar lesions did not contain papillomavirus DNA. In vitro studies showed a possible benefit from acitretin treatment on bone marrow stem cells. However, low-dose acitretin given for 14 months did not prevent the development of an anal squamous carcinoma. Acitretin therapy was, however, associated with a sustained rise in the platelet count.