This study is the first step towards a moder, thorough treatment of the genus Usnea in Mexico. Morphological, anatomical, and chemical features as well as distribution of seventeen Mexican pendulous species collected in temperate forests (1300 to 4000 m) are described. Usnea firma Mot., U. malmei Mot., U. scabrata Nyl. s. lat., and U. subscabrosa Motyka are new records for the country. Usnea goniodes (Stirt.) Motyka is new for the American continent. The following synonyms are proposed: Usnea ceratina Ach. (Syn. nov. U. solida Motyka), U. filipendula Stirton (Syn. nov. U. sublaxa Motyka), U. himantodes (Syn. nov. U. sericea Motyka), U. malmei Motyka (Syn. nov. U. sorediata (Zahlbr.) Motyka), and U. mexicana Vainio (Syn. nov. U. duriuscula Motyka). Usnea sanctaeritae Clerc & Herrera-Campos sp. nov. and U. vitrea Clerc & Herrera- Campos sp. nov. are described. A key for Mexican pendulous species of Usnea is provided