  Dissipative features of dark matter affect its clustering properties and
could lead to observable consequences for the evolution of large--scale
structure. We analyse the evolution of cold dark matter density perturbations
allowing for the possibility of bulk viscous pressure in a causal dissipative
theory. Our analysis employs a Newtonian approximation for cosmological
dynamics and the transport properties of bulk viscosity are described by the
Israel--Stewart theory. We obtain a third order evolution equation for density
perturbations. For some parameter values the density contrast can be suppressed
compared to results obtained in the $\Lambda$CDM scenario. For other values
causal bulk viscous dark matter can exhibit an enhancement of clustering.
