The present disclosure relates to topical treatment of skin diseases, such as psoriasis, atopic dermatitis, alopecia, vitiligo, Reiter's syndrome, pityriasis rubra pilaris, epidermolysis bullosa simplex, palmoplantar keratoderma, pachyonychia congenita, steatocystoma multiplex, cutaneous lichen planus, cutaneous T-cell lymphoma, hidradenitis suppurativa, contact dermatitis, ichthyosis, and a disorder of keratinization, using (a) a JAK inhibitor, or a pharmaceutically acceptable salt thereof, and (b) vitamin D3, a vitamin D3 analog, or a pharmaceutically acceptable salt thereof.