The factors involved in regeneration of the autotrasplanted adrenal cortex were studied experimentally in dogs. On the basis of a number of conditions necessary for the regeneration of adrenocortical tissue, the dogs were divided into 4 groups according to differences in substitution therapy following autotransplantation. The only group to demonstrate long-term survival received an intermittent substitution of cortisone acetate after the completion of 6 days postoperative replacement therapy. The hormonal functions after adrenocortical autotransplantation were examined in the long-term survivers. The secretory function of adrenocortical tissue after autotransplantation was confirmed by the detection of serum concentrations of aldosterone and cortisol, however, estrogens were not detected in the peripheral blood stream following autotransplantation. The negative response to the synthetic ACTH stimulation test observed in this study was evidence of the functional limitation of regenerated cortical tissue. Clinically, however, the procedure performed in this study will be beneficial for patients with advanced and metastatic breast cancer, not only as a form of surgical hormonal therapy, but also as an effective palliative method of treatment.