A vast amount of research has been devoted to understanding the role of the hippocampus in learning and memory. Damage to the hippocampus results in severe cognitive impairments in a broad range of species, including humans and rats. Complementary work has shown that chronic stress, which can result in hippocampal cell death, impairs hippocampal‐specific learning and memory. For example, spatial learning, which is impaired in animals with lesions of the hippocampus, is impaired in chronically stressed animals. Moreover, acute stress also impairs hippocampal‐dependent learning and memory. This chapter reviews our studies on the effects of acute stress on hippocampal‐dependent memory and synaptic plasticity. Our recent findings indicate that exposing rats to a predator, which is an intense stressor, impairs cognitive and electrophysiological measures of hippocampal functioning.