A young woman, who had had a normal pregnancy and delivery more than a year before, was hospitalized for weakness, myalgia, pharyngitis, cough, and fever. The diagnosis was aplastic anemia; the treatment included corticotropin, hydrocortisone, an antibiotic, and transfusion of whole blood. After discharge and several months of improvement, there was a recurrence. During the second hospitalization treatment included antibiotics, mercaptopurine, methotrexate, corticotropin-zinc hydroxide, and prednisolone. A second remission was obtained, during which she received five transfusions. The final hospitalization was for recurrence of severe menorrhagia with ecchymoses, leukemic infiltrations of the skin, and pneumonitis; the blood picture now was that of acute monocytic leukemia. The history illustrates the fact that acute leukemia is sometimes preceded by atypical manifestations, which in this case took the form of aplastic anemia.