SummarySarcoidosis was confirmed by biopsy in 13 out of 16 patients in which the disease was suspected. Hypercalcemia was present in 4 patients, associated with renal insufficiency; hypercalciuria without hypercalcemia was found in 3 patients with a normal glomerular filtration rate; 9 patients had normal serum and urinary calcium. Circulating 1, 25-dihydroxyvitamin D (l,25(OH), D) was increased in hypercalcemic patients, in spite of renal insufficiency. Corticosteroid treatment rapidly normalized l,25(OH)2D levels in a few days, and corrected hypercalcemia. In one patient, the progressive reduction of prednisolone to 2.5 mg/day was followed by the recurrence of hypercalcemia. One patient exhibited before corticotheraPy a recurrent seasonal hypercalcemia. The absence of calcium metabolism abnormalities in about 50% of our patients could correspond in some cases to inactive sarcoidosis and/or to a low level of 25-hydroxyvitamin D, the precursor of l,25(OH)2D, but remained without explanation in other patients. Calcium metabolism abnormalities thus do not appear as a rule in active sarcoidosis with a normal vitamin D supply. Hypercalcemia in sarcoidosis, related to l,25(OH)2D overproduction, seems to occur only in the presence of renal insufficiency. Acta Clin Belg. 42,6; 421–30.