The effects of dexamethasone, cortisol, and deoxycorticosterone on sulfate incorporation by cartilage of normal rats were determined. In vivo dexamethasone was a more potent inhibitor than cortisol, and deoxycorticosterone in the dose tested was ineffective. In vitro dexamethasone and cortisol were inhibitory in concentrations of 10-8 and 10-7M, respectively, when sulfate incorporation was measured after 24 h of incubation. Dexamethasone was at least 10 times as potent as cortisol. Deoxycorticosterone was inhibitory in a concentration of 10-4M. It is concluded that inhibition of mucopolysaccharide synthesis in cartilage of normal rats by adrenal cortical steroids or their analogs, both in vivo and in vitro, is correlated with glucocorticoid activity.