A patient with metastatic breast cancer and secondary myelodysplastic syndrome (MDS) is presented in this article. Pancytopenia and erythroblastic features in the peripheral blood were associated with hypoplasia and diffuse fibrosis in the bone marrow. Strong staining of the reticulin fibers with silver and decreased number of megakaryocytes in the bone marrow were unusual for secondary MDS. It is concluded that there is still more to investigate in this field.