  We generalize the polynomial Szemer\'{e}di theorem to intersective
polynomials over the ring of integers of an algebraic number field, by which we
mean polynomials having a common root modulo every ideal. This leads to the
existence of new polynomial configurations in positive-density subsets of
$\mathbb{Z}^m$ and strengthens and extends recent results of Bergelson, Leibman
and Lesigne on polynomials over the integers.
