This study is the first attempt to review the Usnea fragilescens complex in Mexico. Morphological, anatomical, and chemical characters, as well as distribution are described for nine species. The updated distribution of U. dasaea Stirt. in Mexico is provided. A discriminant analysis of the CMA of the most common species is used to show the reliability of the correlation of anatomical, morphological, and chemical characters in their separation. Usnea brasiliensis (Zahlbr.) Motyka, U. esperantiana Clerc, U. fragilescens Lynge var mollis (Vain.) Clerc, U. jamaicensis Ach., and U. ramillosa Motyka s.str. are new records for Mexico. Usnea brasiliensis is a new record for North America. A key for the U. fragilescens group in Mexico is provided.