  We present a study of the LHC sensitivity to the W boson mass based on
simulation studies. We find that both experimental and phenomenological sources
of systematic uncertainties can be strongly constrained with Z measurements:
the lineshape is robustly predicted, and its analysis provides an accurate
measurement of the detector resolution and absolute scale, while the
differential cross-section analysis absorbs most of the strong interaction
uncertainties. A sensitivity $\delta Mw \sim 7 \MeV$ for each decay channel (W
--> e nu, W --> mu nu), and for an integrated luminosity of 10 fb-1, appears as
a reasonable goal.
