Stroke is the third most common cause of death and the primary cause of morbidity in the United Kingdom. It can be associated with deterioration in both sensorimotor and cognitive skills. Proximal occlusion of the middle cerebral artery (MCAO) in rodents is a widely used model of experimental cerebral ischaemia, which has been used to investigate the effect of stroke on cognition in spatial learning, such as the watermaze. However, findings to-date have been varied, depending on when testing was started after MCAO and the duration of training and testing, raising doubts about the utility of MCAO in rodents to study memory deficits. The present study was designed to discriminate between sensorimotor and spatial memory to establish whether MCAO has a significant influence on both the acquisition and retention of spatial memory. Female Lister Hooded rats (n=10) underwent MCAO. The artery was electrocoagulated from the origin of the lenticulostriate arteries to the inferior cerebral vein and then transected to ensure complete occlusion. Sham animals (n=9) underwent the same procedure except the artery was not occluded or transected and a group of naive, unoperated animals (n=8) was included. Training in the watermaze commenced 10 days after MCAO with 3 days of training to a visible escape platform of varying positions from different start positions. The animals were then trained to find a hidden escape platform at a fixed location (spatial reference memory). The start position was varied and the first trial every day was a probe trial where no platform was present for the first 60 seconds. For acquisition, animals were trained until they spent at least 50% of the probe trial in the quadrant where the platform was normally placed (target quadrant) for 3 consecutive days. The retention of memory was tested 1, 7 and 28 days after this criterion was reached. MCAO induced a consistent infarct involving both cortex and caudate which by 28 days was represented by ipsilateral tissue loss of 32.1 2.8 % of the contralateral hemisphere (mean S.E.M). The watermaze results revealed no deficit in acquisition or retention of memory in MCAO animals compared to sham and naive animals. There was no difference in the average number of days to reach acquisition criterion (Graph 1), and no difference in the proportion of time spent in the target quadrant during the retention tests (Graph 2). Data are presented as mean S.E.M. In conclusion, this study, designed to differentiate between spatial memory and sensorimotor deficits, revealed no evidence for deficits in memory acquisition or retention following MCAO. (See Figure 1).