Bone mineral content was measured by photon absorption densitometry in 25 patients with rheumatic diseases receiving glucocorticoids on an alternate day treatment schedule, and in 25 age-, sex-, and race-matched patients receiving daily steroid therapy. Mean values for cortical (diaphyseal) mass, trabecular (metaphyseal) mass, and the cortical/trabecular mass ratios were not different in the two groups. Steroid-induced osteopenia, defined as an elevated ratio of cortical to trabecular mass, occurred in both therapeutic regimens (8 of 25 on alternate day; 11 of 25 on daily). Therefore, bone loss was demonstrable in individuals on alternate day regimens. Serum levels of calcium, ionized calcium, alkaline phosphatase, and parathyroid hormone were similar in the two groups.