Background: Nickel allergy has been studied by contact dermatitis groups around the world, and the frequency of nickel sensitivity has been reported to be decreasing in some populations. Objective: To review the prevalence of nickel allergy as observed by the North American Contact Dermatitis Group from 1992 to 2004. Methods: The computer database of the North American Contact Dermatitis Group was used to examine the prevalence of nickel allergy over the study period and to analyze it by time, sex, and age. Results: From 1992 to 2004, 25,626 patients were patch-tested. The percentage of women tested was fairly constant (61.4-66.3%). A steady increase in nickel sensitivity was seen from 1992 to 2004. Subgroup analysis did not identify a population with declining nickel allergy. Conclusions: Nickel allergy continues to increase in younger and older men and women patch-tested in North America.