Cholelithiasis has been demonstrated in at least 25% (19) of a series of 75 patients with primary hyperparathyroidism and 88 parathyroid adenomas at the University of Cincinnati Medical Center. This contrasts sharply with an incidence of cholelithiasis of 10% in the general population. Eight of the 19 patients with proved cholelithiasis and primary hyperparathyroidism were less than 30 years of age. In addition, at least six of the 19 patients with cholelithiasis had radiopaque gallstones in contrast to the general incidence of 10% radiopaque calculi. Other clinical manifestations of hyperparathyroidism were renal calculi in 59% (44 patients), peptic ulcer in 27% (20 patients), bone disease in 16% (12 patients), mental disturbance in 12% (9 patients), and pancreatitis or ectopic calcification in only 4% (3 patients) each.