Background: Patch testing is considered to be the standard for diagnosis of delayed-type hypersensitivity reactions of the skin (allergic contact dermatitis). Objective: The objective of this study was to examine the prevalence of patch testing by US dermatologists and associated practice characteristics. Methods: One-third of US Fellows of the American Academy of Dermatology were sampled systematically with a written survey. Responses from this survey were compared with responses from a 1990 survey of dermatologists. Results: Eighty-three percent of responding dermatologists stated that they performed patch testing in their practice. Whereas the majority of patch testing dermatologists (52%) used a 48-hour, 96-hour patch test reading schedule, 26% performed a single reading at 48 or 72 hours. Among patch testing dermatologists, most (74%) used TRUE Test, and many (44%) did so because it was less time consuming for staff. Many dermatologists (46%) felt that they were patch testing more patients now than when TRUE Test was not available. Eleven percent of dermatologists who patch tested also photopatch tested. Conclusions: The proportion of US dermatologists who patch test has significantly increased from 1990 to 1997 (P < .0001). Whereas the majority of US dermatologists patch test, one quarter of those who do so perform only a single reading.