Abstract: Treatment of auto-immune cytopenia refractory to front line therapy with intravenous immunoglobulins and steroids is a matter of concern. We assessed the efficacy and safety of mycophenolate mofetil in a prospective open preliminary study. Study design: Adult patients with steroid refractory auto-immune cytopenias were included. Mycophenolate mofetil (MMF) was added to treatment given at the time of inclusion, and efficacy was evaluated in term of improvement of platelet/haemoglobin levels and in term of reduction of previously given drugs, if any. All auto-immune thrombocytopenic purpura (AITP) patients had serologic assessment for associated auto-antibodies at the time of inclusion. Cytopenias associated with other auto-immune diseases, lymphoproliferative diseases or HIV infection were excluded. Results: From November 1999 through November 2003, 13 patients were included (nine AITP, three auto-immune haemolytic anaemia (AIHA), one Evans’ syndrome; four males, nine females; age: 35–72 yr). For AITP patients, an overall response of 78% was observed. Retrospective analysis showed no significant difference between patients having a short disease duration (<1 yr) and longer disease duration; between patients who previously received more or less than three treatments; and between patients for whom MMF was started as monotherapy or in association with prednisone, However, all AITP patients presenting associated auto-antibodies responded to MMF, while only 50% of patients without associated antibodies were responders. All patients presenting AIHA and Evans’ syndrome were responders. The drug was well tolerated, with no significant side effects reported. The cumulative data suggest a potential place for MMF in the treatment arsenal of refractory cytopenias.