A prospective randomized trial of anthralin in Lassar's paste compared with anthralin in 0.0125% clobetasol propionate in the treatment of chronic plaque psoriasis was undertaken. The psoriatic skin of patients treated with the corticosteroid-anthralin combination cleared significantly more quickly than those treated with anthralin alone, with a mean time to clearance of 14.9 days compared with 18.5 days, and with lower concentrations of anthralin. No significant difference was found in the rate of relapse of the two treatment groups, with relapse occurring in over 80% of patients within one year. Anthralin in 0.0125% clobetasol propionate was found to be an effective agent in the treatment of chronic plaque psoriasis, and one that was cosmetically acceptable to patients and nursing staff. An important disadvantage, however, was the development of a staphylococcal folliculitis in four of the 35 patients in which it was used. Because of this, anthralin in Lassar's paste remains our standard inpatient therapy, although the ease of use and cosmetic acceptability of anthralin in clobetasol propionate make it a useful remedy for outpatient use.