The investigation for correlation between administered sex hormones and changes in the serum Ca levels in elderly individuals was performed in 18 females and 21 males. Ethynylestradiol was given to 10 females and 11 males, and testosterone propionate to 8 females and 10 males. In all instances the level of the serum Ca increased in significance at the 1% level, except for the males on testosterone propionate who showed significant increase at the 2% level. Eight weeks after discontinuance of the sex hormone administration the serum Ca values dropped back to preadministration levels. There was no correlation between the changes of Ca serum values and vaginal smears in the estrogen-treated women.