  We present simulations of the production cross-section measurement of
top-antitop pairs in the di-leptonic decay channel with the ATLAS detector.
This study uses the Commissioning Service Challenge (CSC) data, which is the
latest and centrally produced Monte-Carlo data set to validate the detector
simulation before the actual data taking. The signal process was generated with
MC@NLO and important background processes were studied. A cut and count method
and two likelihood methods were employed to measure the cross section and
important systematic effects were investigated. The expected statistical and
systematic errors for a luminosity of 100 $\ipb$ are also given.
