Ten subjects were assessed using the vasoconstrictor assay technique in a double-blind study in order to evaluate the potencies of several diluted and undiluted proprietary corticosteroid ointments. Results showed that clobetasol propionate 0.05% (Dermovate) ointment at a dilution of one part in ten (clobetasol propionate 0.005%) in white soft paraffin was equipotent with betamethasone valerate 0.1% (Betnovate) ointment; and no difference in potency was demonstrated between beclomethasone dipropionate 0.025% (Propaderm), betamethasone valerate 0.1% (Betnovate) and clobetasone butyrate 0.05% (Eumovate).