Summary The association of Gaucher's disease with chronic lymphocytic leukaemia (CLL) is very rare. To our knowledge only five cases have been reported (Chang-Lo, Yam & Rubenstone 1967; Chang-Lo el al. 1975; Fox et al. 1984; Lee 1982; Mark, Dominguez & Rywlin 1982). We report a patient with this association, the CLL had been diagnosed 12 years after the demonstration of Gaucher's disease.