Over and above the information obtained with screening series of allergens, supplemental allergens can provide additional insight as to which substances a patient has become sensitized. These allergens are commercially available and are sold as a series of related materials. Twelve such series were used over a period of 8.5 years. This report investigates the value of each series in providing additional information not provided by the use of routine screening series of allergens. The most useful additional allergens are identified.