Experiments were conducted on rats to determine (a) whether a single ECS [electroconvulsive shock] produces amnesia either for a behavior which changes merely as a function of exposure, such as open field activity, or for fear induced by a grid shock, and (b) whether a single ECS, alone or after grid shock, induces fear as measured by open field ambulation and defecation. The results show no evidence that ECS produces amnesia, either for previous exposure to the open field, or for fear induced by grid shock. Rather, increased fear following a single ECS was experimentally demonstrated.