Although adoption of skin sensitization in vivo assays for hazard identification is likely to be successful in the next few years, this does not replace their use in potency prediction. Notably, measurement of potency of skin sensitizers in the local lymph node assay has been important. However, this local lymph node assay potency measure has not been formally assessed against a range of substances of known human sensitizing potential, because the latter is lacking. Accordingly, criteria for human data have been established that characterize 6 categories of human sensitizing potency, with 1 the most potent and 5 the least potent; category 6 represents true nonsensitizers. The literature has been searched, and 131 chemicals assigned into these categories according to their intrinsic potency judged only by the available human information. The criteria and data set generated provide a basis for examination of the capacity of nonanimal approaches for the determination of human sensitization potency.