Recent hard QCD results from ATLAS

The LHC provides a new regime to probe perturbative QCD and for which MC generators need to be tested to pave the way for BSM searches. The results of several studies performed in ATLAS using the full 2010 data sample are presented: inclusive jets and dijets cross sections,azimuthal decorrelations, multijets, dijets with jet veto, jet sub-structure, b-jet and prompt-photon production. In addition, some of these observables will become sensitive to alpha_s, can constrain PDFs or reveal new physics