Allergy to latex is a rapidly emerging public health problem. Because our knowledge of the major allergens involved is incomplete, standardized in vivo and in vitro tests have not been available. Because of systemic reactions to skin prick testing, this method should be used only after results of other tests have been inconclusive. Risks and benefits of the test need to be explained to the patient, and until standard extracts of latex are available, skin tests should be performed under a research protocol. We anticipate that with greater knowledge of the relevant allergens, purification of these allergens with affinity chromatography, high-performance liquid chromatography, and monoclonal antibodies, a safe and reliable extract will be available in the near future for skin testing. Until then, the above guidelines can serve clinicians in their daily practice in the diagnosis of latex allergy.