  The mass derived from gravitational lensing reflects the total mass contained
in the lensing system, independent of the specific matter contents and states.
A comparison of the dynamical masses from hydrostatic equilibrium with the
gravitational masses from arc-like images of background galaxies is made for
four clusters of galaxies at intermediate redshits. It is found that virial
analysis has underestimated the total cluster masses (from lensing) by a factor
of $3\sim6$ within a radius of $\sim0.3$ Mpc $h_{50}^{-1}$ around the cluster
centers, indicating that clusters of galaxies might not be regarded as the well
relaxed virialized systems. The increase of the total cluster masses obtained
from lensing leads to the decrease of the baryon fractions of clusters of
galaxies, which provides a crue for solving the ``$\Omega_0$ disprepancy
puzzle" in cosmology.
