  Production of the $K^{\ast}(892)^0$ and $\bar{K}^{\ast}(892)^0$ resonances
was studied via their $K^+ \pi^-$ and $K^- \pi^+$ decay modes in central Pb+Pb,
Si+Si, C+C and inelastic p+p collisions at 158\agev ($\sqrt{s_{NN}}$ = 17.3
GeV) with the NA49 detector at the CERN SPS. Transverse momentum and rapidity
distributions were measured and total yields were estimated. The yield of
$K^{\ast}$ exceeds that of $\bar{K}^{\ast}$ by about a factor of two in
nucleus-nucleus reactions. The total yield ratios $< K^{\ast} >/< K^+ >$ and $<
\bar{K}^{\ast} >/< K^->$ are strongly suppressed in central Pb+Pb compared to
p+p, C+C and Si+Si collisions in agreement with the expected attenuation of
these short-lived resonance states in the hadronic phase of the expanding
fireball. The UrQMD model, although incorporating such a scenario, does not
provide a quantitative description of the experimental results. The statistical
hadron gas model assuming the same freeze-out parameters for stable hadrons and
resonances overestimates the $< K^{\ast} >/< K >$ ratios in central Pb+Pb
collisions by about a factor of 2.5.
