— Research on robotic manipulation has mainly focused on manipulating rigid objects so far. However, many important application domains require manipulating deformable objects, especially deformable linear objects (DLOs), such as ropes, cables, and sutures. Such objects are far more challenging to handle, as they can exhibit a much greater diversity of behaviors. This paper describes a new motion planner for manipulating DLOs and tying knots (self-knots and knots around simple static objects) using cooperating robot arms. The planner constructs a topologically-biased probabilistic roadmap in the DLO’s configuration space. Unlike in traditional motion planning problems, the goal is a topological state of the world, rather than a geometric one. The implemented planner was tested in simulation to achieve various knots like bowline, neck-tie, bow (shoe-lace), and stun-sail.