In a series of 335 renal transplant recipients, 28 patients underwent parathyroidectomy due to secondary hyperparathyroidism. Twenty patients were operated on prior to renal transplantation, 8 subsequent to it. Solitary adenomas were found in 6 cases, diffuse hyperplasia in 22. Fifteen of the patients with diffuse hyperplasia underwent total parathyroidectomy with autotransplantation of parathyroid fragments into the sternocleidomastoid muscle, subtotal parathyroidectomy was performed in 7. Four hypercalcaemic patients underwent parathyroid surgery because of deteriorating transplant function but without improvement. Following parathyroidectomy, 21 patients became hypocalcaemic. 15 of these patients had undergone total parathyroidectomy and autotransplantation. Dihydrotachysterol substitution was accompanied by toxic symptoms in three patients on dialysis and by deteriorating renal function in two transplanted patients. Therefore, subtotal parathyroidectomy is recommended as the surgical procedure of choice in the treatment of secondary hyperparathyroidism before, as well as after renal transplantation.