Abstract : A search for a heavy Standard Model Higgs boson decaying via H->ZZ->llqq, where l=e or mu, is presented. The search uses a data set of pp collisions at sqrt(s) = 7 TeV, corresponding to an integrated luminosity of 4.7 fb^-1 collected in 2011 by the ATLAS detector at the CERN LHC. No significant excess of events above the estimated background is found. Upper limits at 95% confidence level on the production cross section of a Higgs boson with a mass in the range between 200 and 600 GeV are derived. A Standard Model Higgs boson with a mass in the range 300 <= mH <= 322 GeV or 353 <= mH <= 410 GeV is excluded at 95% CL. The corresponding expected exclusion range is 351 <= mH <= 404 GeV at 95% CL.