We have used selenium sulfide extensively, in concentrations varying from 0.5% to 2.5% in lotion, ointment, cream, and jelly vehicles for the treatment of seborrheic dermatitis of the scalp, eyelids, external ear canals, and glabrous skin. The results with all of these formulations of selenium sulfide have been satisfactory in over 80% of the patients treated. The 0.5% and 1% concentrations were less irritating than and equally as effective as the higher concentrations. However, even with the 0.5% and 1% concentrations, aggravations of existing dermatoses or complaints of irritation occurred, particularly in those patients who had acute episodes or extensive eruptions of seborrheic dermatitis; in those who had seborrheic dermatitis superimposed on atopic dermatitis, chronic infectious eczematoid dermatitis, or extensive contact dermatitis, and in those patients who had seborrheic dermatitis complicated by chemical irritation from treatment or coincidental contact agents. It seemed logical,