Chronic lymphocytic leukaemia (CLL) may transform to either malignant lymphoid disorder or increase the occurrence of solid neoplasms. However myeloid malignancies seldom develop. We report a case of a patient who has remained untreated for CLL and developed myelodysplastic syndrome (refracter anemia with ringed sideroblasts) six years after the diagnosis of CLL. Development of myelodysplastic syndrome resulted in concurrent attenuation of CLL. Discussion of the pathogenesis of myeloid disorders occurring with CLL and review of the literature are also presented.