BACKGROUND: This study aimed to determine the effects of sepsis on brain integrity, memory, and executive function. METHODS: Twenty sepsis patients who were not diagnosed with sepsis-associated encephalopathy (SAE) but had abnormal electroencephalograms (EEGs) were included. The control group included twenty healthy persons. A neuropsychological test of memory and executive function and a brain magnetic resonance imaging scan were performed. The volumes of cortex and subcortex were measured using the FreeSurfer software. Acute Physiology and Chronic Health Evaluation Ⅱ(APACHE Ⅱ) score was used to determine the disease severity. RESULTS: In the sepsis group, the levels of immediate free recall, immediate cued recall, and delayed cued recall in the Califia Verbal Leing Test-Ⅱ(CVLT-II) were significantly lower; the explicit memory (recollection process) in the process dissociation procedure test was lower; and the volumes of the left and right hippocampi were significantly lower compared with the control group. The volume of the presubiculum in the hippocampus of sepsis patients showed statistically significant decrease. In the sepsis group, the volumes of the left and right hippocampi were negatively correlated with the APACHE Ⅱ score and positively with immediate free recall, immediate cued recall, and delayed cued recall in the CVLT-II; moreover, the hippocampal volume was significantly correlated with recollection but not with familiarity. CONCLUSIONS: Patients with abnormal EEGs during hospitalization but with no SAE still have reduced hippocampal volume and memory deficits. This finding indicates that sepsis leads to damage to specific parts of the hippocampus.