The efficacy and safety of clobetasol propionate 0.05% scalp application was evaluated in 378 patients with moderate to severe scalp psoriasis in a double-blind vehicle-controlled parallel group study. After 2 weeks of twice-daily applications, 81% receiving active drug versus 22% receiving vehicle had clearing of 50% or greater. Complete clearing was seen in 26% with active drug and 1% with vehicle. Local side effects were primarily burning or stinging in 11% and 10% of patients treated on an active or a vehicle regimen, respectively. The morning cortisol levels of 168 patients were checked at baseline and again after 2 weeks of drug therapy. Subnormal morning plasma cortisol values were seen in 5% of the patients receiving active drug and in 5% receiving vehicle; 13% of those taking active drug versus 5% taking vehicle had a 50% or greater decrease in morning cortisol at the 2-week visit compared with baseline values. Clobetasol propionate 0.05% scalp application appears to be a safe and an effective treatment for scalp psoriasis.