Objective To explore the predictive value of blood urea nitrogen/creatinine ratio (BUN/Cr) for frailty in maintenance hemodialysis (MHD) patients.  Methods  This study was a single centered and cross-sectional study that included 247 patients undergoing MHD treatment in a tertiary hospital in Shanxi province from May 2022 to November 2023. They were divided based on the score of FRAIL scoring system (FRAIL: fatigue, resistance, ambulation, illness, and loss of weight) into two groups, frailty group (FRAIL score≥3, n=101) and non-frailty group (FRAIL score ≤2, n=146). Their relevant information was collected. Univariate and binary logistic regression were used to find out the influencing factors for frailty in the MHD patients. Receiver operating characteristic (ROC) curve was used to analyze the diagnostic value of BUN/Cr for frailty in MHD patients.  Results  Age, dialysis age, C-reactive protein, blood urea nitrogen and BUN/Cr were higher in frail group than in non-frail group (t/χ2/Z=9.042, -4.612, -2.649, 3.096 and 14.724 respectively; P＜0.001, ＜0.001, 0.008, 0.002 and ＜0.001 respectively). Body mass index, hemoglobin, serum albumin, creatinine, and urea clearance index were lower in frail group than in non-frail group (t/χ2/Z= -2.294,  -2.769,   -8.936, -13.126 and -5.097 respectively; P=0.022, 0.006, ＜0.001, ＜0.001 and ＜0.001 respectively). Binary logistic regression demonstrated that age (OR=1.060, 95% CI: 1.015～1.107, P=0.009), dialysis age (OR=1.283, 95% CI:1.022～1.612, P=0.032), serum albumin (OR=0.841, 95% CI: 0.748～0.945, P=0.004), C-reactive protein (OR=1.641, 95% CI: 1.039～2.591, P=0.033), urea clearance index (OR=0.013, 95% CI: 0.001～0.251, P=0.004), and BUN/Cr (OR=3.478, 95% CI: 1.455～8.310, P=0.005) were the independent risk factors for frailty in the MHD patients. ROC curve suggested that the optimal value of BUN/Cr for the diagnosis of frailty in MHD patients was 9.42, with the area under the curve of 0.929 (95% CI: 0.896～0.962, P＜0.001).  Conclusion  BUN/Cr has a better prediction value for the presence of frailty in MHD patients. It also provides a new perspective for medical professionals to identify frailty.