Food allergy is a recognized clinical entity in dogs and cats and is an important differential to consider in the workup of a pruritic animal. Food can be a trigger factor for canine atopic dermatitis, and food allergy may coexist with feline atopic skin syndrome. Other clinical signs such as urticaria, recurrent pyoderma, and dorsolumbar pruritus can be seen in dogs, and urticaria, conjunctivitis, and respiratory signs can be seen in cats. In both species, gastrointestinal signs may be present. The pathogenesis in dogs and cats is complex and incompletely understood, which limits the development of reliable diagnostic laboratory tests. The diagnosis currently relies on an appropriately performed diet trial with subsequent provocation. This paper briefly reviews food allergies in people and explores our current knowledge of the disorder in dogs and cats.