A 76-year old patient was referred to our Oncology Unit due to hepatosplenomegaly, anemia, thrombocytopenia, eosinophilia, elevation of lactat dehydrogenase and leucocytosis with occurrence of myeloid and erythroid precursors in the peripheral blood. Histopathological examination of the bone marrow and molecular genetics showing a c-kit-D816V-mutation confirmed the diagnosis of systemic mastocytosis without evidence of idiopathic myelofibrosis. After starting of prednisone treatment anemia, thromocytopenia and the patient's performance status rapidly improved.