  The measurement of the missing transverse energy Etmiss is fundamental for
many analyses at LHC. Good Etmiss resolution and calibration are essential for
searches of new physics as well as precise measurements. We describe a refined
reconstruction and calibration of Etmiss developed by ATLAS and its
performances on events containing Z and W bosons. The data sample was collected
in proton-proton collisions at a center-of-mass energy of 7 TeV, and
corresponds to an integrated luminosity of about 36 pb-1. The determination of
the absolute scale of the Etmiss, fundamental for determining systematic
uncertainties in all analysis involving Etmiss measurements, is also presented.
