  A measurement is reported of the production cross section of top-quark pairs
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-tbar production cross section sigmattbar=176 +/-5 (stat) +14
-11 (syst) +/- 8 (lum.) pb is measured for an assumed top-quark mass of m_t =
172.5 GeV.
