To the Editor.— Sensitivity to hydrogenated lanolin has not been described previously. I should like to report two cases where patients reacted to this substance used in the base of a steroid ointment, betamethasone valerate (Betnovate [Britain]). This contains betamethasone 17 valerate, 0.12%; hydrogenated lanolin, 10%; liquid paraffin, 10%; and white soft paraffin made up to 100%. CASE 1.— A 68-year-old man had had pemphigoid for 3½ years which was controlled with prednisone, 5 mg daily. Occasional blisters were treated with an ointment of betamethasone valerate and neomycin sulfate (Betnovate-N [Britain]). In January 1969, a large area of erythema and vesiculation developed on the forearm where he had applied the ointment. There was also marked edema. As soon as he stopped using the ointment the eruption subsided rapidly. Patch testing showed the following reactions at 48 and 96 hours: Betamethasone valerate and neomycin sulfate ointment (Betnovate-N [Britain]) + + + Betamethasone valerate and