Two-hundred and fifty patients undergoing initial exploration for primary hyperparathyroidism were analyzed for differences in clinical presentation, biochemical status, pathology, and outcome of surgery. In patients less than 60 years of age (younger patients, n = 119) the most common preoperative symptoms and signs were fatigue (40.3%), bone pain (33.6%), renal stones (31.0%), hypertension (27.7%), and psychiatric illness (27.7%). In patients greater than or equal to 60 years of age (older patients, n = 131) the most frequent symptoms and signs were hypertension (46.6%), fatigue (35.1%), bone pain (30.5%), muscle weakness (28.2%), and joint pain (22.9%). Renal stones were 2.6 times more common (p less than 0.001, chi 2) in younger patients and hypertension 1.7 times more common (p less than 0.05, chi 2) in older patients. There was no significant difference in the preoperative and postoperative laboratory values typically associated with primary hyperparathyroidism. Double adenomas were more common in older (9.2%) than in younger patients (2.5%, p less than 0.05, chi 2). Surgical cure was obtained in 98.8% of patients, and after parathyroidectomy 83% of the younger and 82% of the older patients experienced substantial relief of pre-operative symptoms. Specific questioning revealed most patients to be symptomatic and older patients appear to receive the same clinical and metabolic benefits from parathyroidectomy as younger patients.