Flocculation of colloidal suspensions is often induced by the addition of small amounts of polymers. When a high-molecular-weight polymer chain adsorbs onto two or more particles to bind them together, the effect is referred to as polymer bridging or bridging flocculation. In polymer bridging, more than one polymer molecule is required to bridge large particles, whereas for small particles, only a small segment of a polymer chain is required, and thus one molecule can extend through many bridges. Because of long-range interactions and great variety of conformation, the suspensions flocculated by polymer bridging show very interesting rheological behaviour which is quite different from ordinary flocculated systems. The present review concerns four unique rheological effects which were found by authors. Although the rheological properties of flocculated suspensions are generally determined by the dynamic structures of gross flocs in shear fields, the unique rheology can be directly explained in connection with the mechanical properties of the bridge between two primary particles. The relations between the interparticle forces and rheological properties of suspensions will be discussed as a function of adsorption affinity of polymer for the particle surface and the bridging conformation. The bridging flocculation is very attractive as a new technique in rheology control of colloidal suspensions.