In this paper the effect of source and receiver position uncertainty on multistatic active sonar localisation accuracy is examined. In the general multireceiver, multisource case, the localisation performance of a multistatic active system is highly dependent on the actual geometry under consideration. Here, we focus on two single-source geometries: the basic bistatic geometry with a single receiver and a cooperative monostatic geometry with two receivers, one of which is colocated with the source. We also discuss both the centralised and decentralised multistatic localisation problems. A general procedure for computing the expected localisation accuracy is also presented.