Patients with aplastic anemia were treated with a combination of depo-testosterone cyclopentylpropionate(Upjohn) and dexamethasone. In 7 of 15 patients treated, there was response in which either a significant increase in hemoglobin concentration, a prolonged interval or a cessation of blood transfusion requirement developed during androgen therapy. Younger patients with cellular marrow appeared to be better responding to androgen. EEI(Effective Erythropoietic Index) formulated by Gardner & Nathan(1966) which was a helpful measurement as to whether patients with myelofibrosis whould respond to androgen, was evaluated in patients with aplastic anemia. It was concluded that EEI as well as ferrokinetics indices (Plasma-$^{59}Fe$-disappearance rate, RBC $^{59}Fe$ net incorporation) did not significantly correlate with the degree of response to androgen in aplastic anemia.