The use of a standard series of 37 allergens was evaluated in a retrospective study of 817 consecutive patients seen between April 1988 and January 1993 at the Skin and Cancer Foundation, Melbourne, Australia. Of the 316 patients with clinically relevant patch test results, 134 (42%) reacted to an allergen in the standard series alone, while an additional 122 (39%) had reactions to allergens in both the standard and supplementary series. The remaining 60 (19%) patients reacted only to allergens in the supplementary series. These data suggest that the use of our standard series alone will detect about 80% of allergic contact dermatitis cases, but that many of these may be insufficiently evaluated. Use of supplementary allergen testing in a specialised clinic is recommended for patients who may have allergic contact dermatitis.