Objective:To observe the correlation between red blood cell volume distribution width (RDW) and cognitive dysfunction in maintenance hemodialysis (MH) patients.Methods:Eight MH patients from January 2019 to January 2020 in the Affiliated Hospital of Jining Medical University were selected. Among them, 48 patients had cognitive dysfunction (Montreal cognitive assessment scale score<26 scores), and 32 patients had normal cognitive function. The relevant clinical data were collected, and multivariate Logistic regression was used to analyze the independent risk factors affecting cognitive dysfunction in MH patients. Receiver operating characteristic (ROC) curve was drawn to evaluate the diagnosis efficacy of RDW in cognitive dysfunction in MH patients.Results:The proportion of diabetes mellitus, incidence of hypotension events and RDW in patients with cognitive impairment were significantly higher than those in patients with normal cognitive function: 43.7% (21/48) vs. 31.2% (10/32), 35.4% (17/48) vs. 25.0% (8/32) and 0.149 ± 0.087 vs. 0.139 ± 0.042, and there were statistical differences ( P<0.05). Multivariate Logistic regression analysis result showed that diabetes and RDW were independent risk factors for cognitive dysfunction in MH patients ( OR = 2.217 and 3.713, 95% CI 0.548 to 8.968 and 1.952 to 7.564, P = 0.030 and 0.011). ROC curve analysis result showed that the area under curve of RDW for the cognitive dysfunction diagnosis in MH patients was 0.791 (95% CI 0.688 to 0.893), the optimal cut-off value was 0.144, the sensitivity was 66.7%, and the specificity was 87.5%. Conclusions:Elevated RDW is an independent risk factor for cognitive dysfunction in MH patients, and it has a good predictive effect on cognitive dysfunction in MH patients.