Background. Surgery for hyperparathyroidism is associated with high cure rates and low morbidity and mortality when performed by experienced surgeons. We wanted to determine whether referral of patients with hyperparathyroidism to an endocrine surgery center has an impact on patient outcomes and costs. Methods. Data from 901 patients who underwent parathyroidectomy recorded in the Maryland inpatient discharge database between 1990 and 1994 at 52 hospitals were compared with 169 consecutive patients who underwent surgical exploration by one surgeon (R.U.) at the Johns Hopkins Hospital. Results. Although in 47 of 52 hospitals fewer than 10 parathyroidectomies were performed each year, in these hospitals four of five related deaths occurred before patient discharge. The percentage of parathyroidectomies in Maryland performed by one endocrine surgeon has increased from 8% in 1990 to 21% in 1994 and is associated with a 97% cure rate and no mortality. Moreover, while hospital length of stay (LOS) in the state has decreased from 7 to 3.1, LOS for the high-volume provider has declined to a mean of 1.3 days. Conclusions. Patients with hyperparathyroidism are increasingly referred to an endocrine surgery center, which results in a high cure rate, low morbidity, no mortality, and a shorter LOS. Improved surgical outcomes and lower costs depend on an experienced surgeon and argue for the referral of these patients to endocrine surgery centers.