Towards Measurement of the Top Quark Cross Section on ATLAS

We present work related to the measurement of the top quark cross section at 7 TeV using the leptons plus jets decay channel at the ATLAS experiment at the CERN LHC. An event selection for top quark pairs is described. Estimates for top quark signal and backgrounds expected with 10 pb-1 of data are given as well as estimates for some of the most important systematic errors. Comparison between data and Monte Carlo expectations are shown.