A 4-year-old Airedale Terrier that had developed estrogen-induced aplastic anemia had a complete recovery after supportive treatment and weekly administrations of nandrolone decanoate. The anemia was induced iatrogenically by administration of estradiol cypionate (2 mg, IM each time) at 48- to 72-hour intervals. Clinical signs included lethargy, anorexia, and weakness; hemoglobin was 6.8 g/dl, PCV was 21%, and WBC was 1,500/dl. Supportive treatment included blood transfusions and administration of antibiotics, corticosteroids, and vitamins. Hematologic values returned to normal by day 81, and the dog has remained healthy for one year after treatment.