The Triassic paleoflora of cerro Cacheuta, Mendoza Province, Argentina. Bryopsida, Lycopsida, Sphenopsida, Filicopsida and Gymnospermopsida (Corystospermales and Peltaspermales). Four stratigraphic logs were measured in detail at the Cacheuta hill (northwestern Mendoza Province, Argentina), and seven plantiferous levels were determined at Puesto Míguez and Agua de las Avispas. The systematic study of the paleoflora found in these localities is presented in this paper. Bryopsida, Lycopsida, Sphenopsida, Filicopsida and Gymnospermopsida (Corystospermales y Peltaspermales) are analized in this first contribution. The systematic study include 25 taxa identified as Muscites guescelini Townrow, Pleuromeia sp., Equisetites fertilis (Frenguelli) Frenguelli, Neocalamites carrerei (Zeiller) Halle, Nododendron suberosum Artabe et Zamuner, Asterotheca truempyi Frenguelli, Cladophlebis copiosa Frenguelli, C. grahami Frenguelli, C. kurtzi Frenguelli, C. mendozaensis (Geinitz) Frenguelli, C. mesozoica (Kurtz) Frenguelli, Coniopteris harringtoni Frenguelli, Dicroidium argenteum (Retallack) Gnaedinger et Herbst, D. lancifolium (Morris) Gothan, D. odontopteroides (Morris) Gothan, D. pinnis-distantibus (Kurtz) Frenguelli, Zuberia feistmanteli (Johnston) Frenguelli emend. Artabe, Johnstonia coriacea (Johnston) Walkom, J. stelzneriana (Geinitz) Frenguelli, Xylopteris argentina (Kurtz) Frenguelli, X. elongata (Carruthers) Frenguelli, Scytophyllum argentinum (Frenguelli) Morel et al. comb. nov. emend., Pachydermophyllum dubium (Burges) Retallack, P. pinnatum (Walkom) Retallack and P. praecordillerae (Frenguelli) Retallack.