  We present a measurement of the muon charge asymmetry from the decay of the
$W$ boson via W to mu nu using 7.3 fb^{-1} of integrated luminosity collected
with the D0 detector at the Fermilab Tevatron Collider at sqrt{s} = 1.96 TeV.
The muon charge asymmetry is presented in two kinematic regions in muon
transverse momentum and event missing transverse energy: (p^{\mu}_{T} > 25 GeV,
\met > 25 GeV) and (p^{\mu}_{T} > 35 GeV, \met > 35 GeV). The measured
asymmetries are compared with theory predictions made using three parton
distribution function sets. The predictions do not describe the data well for
p^{\mu}_{T} > 35 GeV, \met > 35 GeV, and larger values of muon pseudorapidity.

High Energy Physics - Experiment