Despite rapid advances in understanding of the biology of allergic disorders, practical techniques for evaluating the allergic patient remain fairly constant. The AMA Guides to the Evaluation of Permanent Impairment (AMA Guides) requires appropriate assessment before an examiner diagnoses the disorder, determines causation, evaluates whether the patient has reached maximal medical improvement, and rates permanent impairment, if any. A careful history includes both occupational and environmental assessment. Patients with allergic occupational asthma typically must be removed from exposure to the allergen. The environmental assessment should determine the nature of the patient's dwelling, its construction material, heating and ventilation, and the presence or absence of a damp basement, pets, rodents or cockroaches, or hobbies performed in the home. A physical examination should focus on the eyes, nose, lungs, and skin and should exclude obstructive sleep apnea. A thorough medical evaluation always is required, and assessment of immunologic sensitization involves diagnostic allergy skin testing or laboratory assessment. Although the allergens used in such tests are purified and the tests themselves increasingly are standardized, concerns remain regarding nonstandardized laboratories and remote testing. Spirometry is an essential element in objectively defining the nature and severity of respiratory complaints; rhinolaryngoscopy helps differentiate asthma from laryngeal dysfunction and can evaluate sinus disease; and limited cut CT of the sinuses is more cost effective than plain sinus films.