  The $\phi$ meson spectrum, which in vacuum is dominated by its coupling to
the $\bar{K} K$ system, is modified in nuclear matter. Following a model based
on chiral SU(3) dynamics we calculate the $\phi$ meson selfenergy in nuclear
matter considering the $K$ and $\bar{K}$ in-medium properties. For the latter
we use the results of previous calculations which account for $S-$ and $P-$wave
kaon-nucleon interactions based on the lowest order meson-baryon chiral
effective Lagrangian, and this leads to a dressing of the kaon propagators in
the medium. In addition, a set of vertex corrections is evaluated to fulfill
gauge invariance, which involves contact couplings of the $\phi$ meson to
$S-$wave and $P-$wave kaon-baryon vertices. Within this scheme the mass shift
and decay width of the $\phi$ meson in nuclear matter are studied.
