Three patients with vitamin D‐dependent rickets type II were given massive doses of 1α‐hydroxyvitamin D3for 29 to 36 months and their calcium‐phosphate balance was studied during treatment and one month after cesation of treatment. During treatment fasting hypercalciuria was observed in patient 1 and an increased rate of calcium excretion after calcium loading in patients 1 and 2. In these patients, calcium excretion was parallel with the serum 24, 25‐dihydroxyvitamin D. These findings suggested that the responsiveness to 1,25‐dihydroxyvitamin D improved during long‐term treatment of these two patients with vitamin D‐dependent r