This chapter examines the extent to which an ischemically induced spatial memory performance deficit, in adult Mongolian gerbils, is ameliorated by hippocampal neurons, derived from fetal gerbils that are bilaterally transplanted into the CA1 field of the ischemic dorsal hippocampal formation. In an experiment described in the chapter, transient cerebral ischemia was produced in 80–100 g adult male Mongolian gerbils. At the end of the ischemic interval, the clips were released and blood flow was observed to resume through each artery. Non-ischemic gerbils, serving as sham-operated controls, underwent the same surgical procedure except that the common carotid arteries were not occluded. The spatial probe test is used. After the spatial probe test, the ischemic gerbils were ranked according to the severity of their spatial memory performance deficit. Similarly, they were ranked on the basis of performance in an open field and a passive avoidance paradigm. When the number of platform crossings in the training quadrant prior to and after transplantation was determined, it was found that the ischemic gerbils that had undergone bilateral transplantation of a cell suspension derived from whole fetal hippocampi into the CA1 field of the dorsal hippocampal formation had a significant improvement in their performance during the spatial probe test.