Electrophysiological studies have shown that single cells in the hippocampus respond during spatial learning and exploration^1–4, some firing only when animals enter specific and restricted areas of a familiar environment. Deficits in spatial learning and memory are found after lesions of the hippocampus and its extrinsic fibre connections^5,6 following damage to the medial septal nucleus which successfully disrupts the hippocampal theta rhythm⁷, and in senescent rats which also show a correlated reduction in synaptic enhancement on the perforant path input to the hippocampus⁸. We now report, using a novel behavioural procedure requiring search for a hidden goal, that, in addition to a spatial discrimination impairment, total hippocampal lesions also cause a profound and lasting placenavigational impairment that can be dissociated from correlated motor, motivational and reinforcement aspects of the procedure.