The World Health Organization advocates 2 leprosy treatment regimens on the basis of disease classification (as multibacillary or paucibacillary) by skin lesion count. This method, which, in the Philippines, results in a high prevalence (78%) of patients with multibacillary leprosy, was directly compared with classification using standard histopathological and microbiological criteria in 264 currently untreated patients with leprosy. Of those whose leprosy was classified as paucibacillary, 38%-51% of patients had multibacillary leprosy according to classic criteria and were thus at risk of undertreatment according to World Health Organization recommendations.