The frequency of gallstone disease was studied in a group of 82 subjects (69 females and 13 males; mean ages 55-0 and 52-3 years, respectively) with verified hypercalcaemia (VHC) detected in a health screening in the Stockholm area. All non-cholecystectomised subjects were examined with a peroral cholecystography. Causes of hypercalcaemia other than primary hyperparathyroidism (PHPT) had been excluded as far as possible. Sixty-two patients had been operated upon and all but two males were found to have parathyroid adenomas. The patients were compared with a series of 82 normocalcaemic age- and sex-matched subjects, selected from the health screening register. The patients with VHC and/or PHPT had about the same frequency of gallstone disease as the controls. The results are at variance with those of other investigators who have reported that PHPT is associated with an abnormally high frequency of gallstone disease. Possible explanations of the discrepancy in results is discussed.