Rhodobryum (Schimp.) Limpr. is studied for Argentina, based on herbarium specimens and on specimens collected during field expeditions from 2005 to 2008. Two species are recognized for the Argentinian bryological flora. Rhodobryum beyrichianum (Hornsch.) Müll. Hal. is widely distributed in the mountainous areas of northern Argentina and is a new record for the provinces of Corrientes, Tucumán and Salta. Rhodobryum subverticillatum Broth. is reported for the first time for Argentina; it occurs in Jujuy and Salta provinces. Rhodobryum roseolum (Müll. Hal.) Paris, known from a single Argentinian specimen, is excluded from the flora and synonymized with R. beyrichianum. Rhodobryum aubertii (Schwägr.) Brid. and R. roseum (Hedw.) Limpr. are excluded from the bryoflora of Argentina. The status of R. platense (Müll. Hal.) Paris remains obscure; it possibly is not a species of Rhodobryum. Key, descriptions, illustrations, SEM photographs and distribution maps are provided, and habitat ecology and the distribution in Argentina and total distribution are given. Rhodobryum ontariense (Kindb.) Kindb. is recorded first time for Bolivia and Peru. Rhodobryum dentatum (Ochi) T. J. Kop. & Fuertes is a new combination and lectotype is selected for Bryum hieronymi Müll. Hal.