Calcium-regulating hormones were serially measured during the second pregnancy in a woman with pseudohypoparathyroidism type 1b. Calcium levels corrected for serum albumin were maintained almost normal during her second pregnancy with 1alpha-hydroxycalciferol (2.0 microg daily) though they were slightly decreased in late pregnancy. 1,25-Dihydroxyvitamin D levels were higher in early and mid-pregnancy, but not in late pregnancy compared to those after delivery. Parathyroid hormone levels were higher in late pregnancy than after delivery.