  The Lifshitz formula for the dispersive forces is generalized to the
materials, which cannot be described with the local dielectric response.
Principal nonlocality of poor conductors is related with the finite screening
length of the penetrating field and the collisional relaxation; at low
temperatures the role of collisions plays the Landau damping. The spatial
dispersion makes the theory self consistent. Our predictions are compared with
the recent experiment. It is demonstrated that at low temperatures the
Casimir-Lifshitz entropy disappears as $T$ in the case of degenerate plasma and
as $T^2$ for the nondegenerate one.
