  We analyze the recurrence probability (P\'olya number) for d-dimensional
unbiased quantum walks. A sufficient condition for a quantum walk to be
recurrent is derived. As a by-product we find a simple criterion for
localisation of quantum walks. In contrast to classical walks, where the
P\'olya number is characteristic for the given dimension, the recurrence
probability of a quantum walk depends in general on the topology of the walk,
choice of the coin and the initial state. This allows to change the character
of the quantum walk from recurrent to transient by altering the initial state.
