To investigate the methylation of NMUR1 (neuromedin U receptor 1) in breast invasive cancer (BRCA) and its prognostic role in prognosis, the UALCAN database was used to analyze the expression level of NMUR1 in TCGA (the cancer genome atlas)-BRCA tissues, and The Human Protein Atlas database was used for verification. SurvivalMeth database was used to analyze the methylation levels of NMUR1 in BRCA, and COX regression analysis and Kaplan-Meier survival analysis were conducted to study the correlation between the methylation levels of NMUR1 and the prognosis of BRCA patients. In the UALCAN database, 1?097 TCGA breast cancer tissue and 114 normal breast tissue were included, and NMUR1 expression was significantly down-regulated in breast tissue compared with normal breast tissue (P<0.001). The methylation analysis showed that NMUR1 had significant differences in the methylation levels of cg00143376, cg01649597, cg02204630, cg10042319, cg16297948, cg17207690, cg18250832, cg18877969, cg19077400, cg21424120 and cg26913833 in BRCA tissues (P<0.001). Kaplan-Meier survival analysis showed that the survival rate of NMUR1 patients in the high-risk CpG island methylation group (n=320) in BRCA tissues was significantly lower than that in the low-risk group (n=461) [HR=2.1403, 95%CI (1.305 4, 3.509 1), P=0.001]. Compared with the low-risk group, the CpG island methylation level was higher in the high-risk group at cg18877969 (P=0.015), cg16297948 (P=0.028), cg19077400 (P=0.011), and cg26913833 (P=0.035). NMUR1 is hypermethylated in BRCA tissues, and CpG island methylation of NMUR1 is related to the prognosis of BRCA patients, that providing evidence for NMUR1 as a new target for BRCA prognosis and/or treatment.