Classical primary hyperparathyroidism (PHPT) was a multisystem disorder with clear neurologic, psychiatric, gastrointestinal, and cardiovascular consequences. The nature and extent of involvement of these target organs in the modern presentation of the disease are controversial. Although hypertension has been associated with PHPT, it is not cured after parathyroidectomy, nor is it easier to control. Despite significant data on European patients, information on the incidence of cardiovascular abnormalities in American patients with mild disease are limited. Investigation is turning to more subtle abnormalities, such as vascular reactivity and endothelial function, where data are conflicting. Many patients complain of nonspecific neuropsychiatric symptoms. This has been a difficult area to study quantitatively. Classical neuromuscular disease is rare in mild PHPT, although weakness and easy fatigability remain common complaints. These nonspecific symptoms may or may not improve with surgery. While no clear causal association exists between sporadic PHPT and peptic ulcer disease, this is not the case in patients with multiple endocrine neoplasia type 1 (MEN1). Gastrinoma is more severe in those with coexisting PHPT, and Zollinger-Ellison Syndrome improves with treatment of PHPT. Further efforts are necessary to characterize the cardiovascular and neuropsychological profiles of mild PHPT and to determine the longitudinal course of such alterations. With available data suggesting that many asymptomatic patients with PHPT can be safely followed without parathyroidectomy, this information will be of key importance in the management of such individuals.