  The mean square end-to-end distance of a N-step polymer on a Bethe lattice is
calculated. We consider semiflexible polymers placed on isotropic and
anisotropic lattices. The distance on the Cayley tree is defined by embedding
the tree on a sufficiently high dimensional Euclidean space considering that
every bend of the polymer defines a direction orthogonal to all the previous
ones. In the isotropic case, the result obtained for the mean square end-to-end
distance turns out to be identical to the one obtained for ideal chains without
immediate returns on an hypercubic lattice with the same coordination number of
the Bethe lattice. For the general case, we obtain the asymptotic behavior in
the semiflexible and also in the almost rigid limits.
