While there is little doubt that the particle discovered in July 2012 by the ATLAS and CMS collaborations is a Higgs boson, the question of its SM nature is tackled through the measurement of its properties: spin, parity, and couplings. The study of its fermion decay modes is an important part of this research programme, as evidenced by a number of analyses performed on the LHC Run 1 data by the ATLAS collaboration. This talk will present the latest updates of these analyses. Evidence of the coupling of the Higgs to fermions has been obtained in the tau-tau decay mode. A search for the decay of the Higgs boson to bbar has been performed by looking for its associated production with a vector boson or a pair of top quarks. The results of a search for the decay of the Higgs to a pair of muons will also be presented.