Impairment in marrow function often characterizes the evolution of myelodysplastic syndrome. As a differentiating agent, interferon alpha 2a (INF alpha) has been shown to be active in the correction of cytopenias related to myelodysplastic syndromes (MDS). We report the clinical course of 9 patients with MDS treated with low-dose subcutaneous INF alpha (1 x 10(6), 3 times per week). A significant effect on anemia was only demonstrated in one patient (11%). In the other, eight, therapy was totally ineffective and four of them could not receive the complete treatment due to worsening cytopenias or leukemic transformation. In conclusion, in our study, INF alpha had only limited activity in the treatment of myelodysplastic syndrome.