  Charged Higgs bosons are predicted in several extensions of the Standard
Model, where the Higgs sector contains more than one doublet of complex
scalars, for instance in the Minimal Supersymmetric Standard Model (MSSM). For
$m_{H^+} < m_{\mathrm{top}}$, the dominant production mode for charged Higgs
bosons at the LHC is via the decay $t\rightarrow bH^+$ of one of the top quarks
in $t\bar{t}$ events. We present results on the search for such light charged
Higgs bosons in the ATLAS experiment, with emphasis on the decay $H^+
\rightarrow \tau \nu$.
