  In supersymmetric scenarios where the scalar tau lepton is stable or
long-lived, a search for a decay mode chi0 --> stau + mu at the LHC has a good
sensitivity to the flavor mixing in the scalar lepton sector. We demonstrate
that the sensitivities to the mixing angle at the level of sin(theta)=0.15 are
possible with an integrated luminosity of 100fb^{-1} if the total production
cross section of supersymmetric particles is of the order of 1pb. The
sensitivity to the mixing parameter can be better than the experimental bound
from the tau --> mu + gamma decay depending on model parameters.
