A preliminary survey of the bryophyte flora of the Reserva Biológica San Francisco (1 800-3 150 m) in the Andes of southern Ecuador yielded 305 species: 190 hepatics, 112 mosses and 3 hornworts. 63 species are reported new to Ecuador, most of them hepatics. Noteworthy records of rare species include Pleurozia paradoxa (Jack) Schiffn. and P. heterophylla Steph. ex Fulford (Hepaticae: Pleuroziaceae), which are abundant in shrubby upper montane vegetation dominated by Purdiaea nutans Planch. (Cyrillaceae). About 70% of the species are widespread tropical ones (neotropical or pantropical), 21% are Andean species and 4% are of temperate origin. Endemism (1%) is very low. Species range sizes decrease towards higher elevations.