PetSmart doesn't technically sell Rx diets of any kind because like a medicine, you need to get it from a Dr. But, many PetSmarts have Banfields Vet clinics and they sell prescription diets. There are also many varieties of hypo-allergenic foods available that are not prescription. I personally am leery about many prescription diets because they are usually full of fillers and by-products. But, it depends on the allergy and severity of it, and what your Vet advises.