From October 1981 to the end of 1984, 13 patients with primary hyperparathyroidism (PHPT) and 17 with secondary hyperparathyroidism (SHPT) received fresh autografts of diseased parathyroid tissue into their subcutaneous abdominal adipose tissue. Because of previous surgery to treat hyperparathyroidism (HPT) (23%), concomitant thyroid surgery (26%), and a high proportion of multiglandular disease (73%), the patients were at high risk for HPT. During the follow-up period, hypercalcemia was diagnosed in five patients and successfully treated in four: by graft excision in two patients, by excision of a fourth gland from the neck in one patient, and with prednisolone in a patient with sarcoidosis. At follow-up (an average of 30 months after grafting), one patient had HPT and 29 others were euparathyroid. Parathyroid tissue can survive and function in adipose tissue, as was demonstrated by normocalcemia in 14 patients (whose only probable remaining parathyroid tissue had been transplanted into fat), by the demonstration that graft-dependent hypercalcemia could be eliminated by excision of the transplant, and by the demonstration of viable parathyroid tissue by microscopic examination of excised grafts. Autotransplantation of diseased parathyroid tissue into fat is simple and reliable. In cases of recurrent HPT, all or a portion of the graft can be removed while the patient is under local anaesthesia. If infiltrating growth occurs, broad excisions can be performed without sacrificing vital structures.