A bstract A measurement is reported of the production cross section of top-quark pairs ( t $\overline t$ ) in proton-proton collisions at a center-of-mass energy of 7 TeV recorded with the ATLAS detector at the LHC. Candidate events have a signature consistent with containing two isolated leptons, large missing transverse momentum, and at least two jets. Using a data sample corresponding to an integrated luminosity of 0.70 fb −1 , a t $\overline t$ production cross section ${\sigma_{t\overline t }} = {176}\pm {5}\left( {{\text{stat}}.} \right)_{ - {11}}^{ + 14}\left( {{\text{syst}}.} \right)\pm {8}\left( {{\text{lum}}.} \right)$ pb is measured for an assumed top-quark mass of m t = 172 . 5 GeV. This measurement is in good agreement with Standard Model predictions.