Search for a Dark Matter Candidate with the ATLAS Detector

Supersymmetry is an appealing theory beyond the Standard Model which provides a natural Dark Matter candidate. First ATLAS searches for signals of supersymmetry in proton-proton collisions at the LHC are reported here for the 0- and 1-lepton channels; the full data sample recorded in the 2010 LHC run, corresponding to an integrated luminosity of 35 pb^{-1} , has been analysed.