Aplastic anemia is a rare complication of thymoma and is properly documented in only few cases. Here, we report the case of a previously healthy, 65-year-old patient who was found simultaneously to have a spindle-cell thymoma and severe hypoplastic anemia with a mild infiltration of the bone marrow by CD4+ and CD8+ T lymphocytes, CD16+ natural killer cells, and a decrease in blood CD4/CD8 ratio. Cultures of marrow erythroid progenitors demonstrated serum inhibitor. While steroids, cyclophosphamide and antilymphocyte globulin failed to improve hematopoiesis, cyclosporine A (Cy-A) led to a partial, stable remission that was sustained for 4 years. Since Cy-A has been associated with good responses in three cases of thymoma-associated red cell aplasia, we recommend its use in cases of thymoma-associated cytopenias refractory to steroids and cyclophosphamide.