BACKGROUND: Sodium-23 magnetic resonance imaging ((23)Na MRI) allows the measurement of skin sodium concentration ([Na(+)]). In patients requiring dialysis, no data are available relating to the clinical outcomes associated with skin sodium accumulation or the determinants of increasing deposition. METHODS: This was an exploratory, observational study of adult hemodialysis (HD) and peritoneal dialysis (PD) patients. Participants underwent skin [Na(+)] quantification with leg (23)Na MRI at the study's beginning. Outcomes of interest were all-cause mortality and composite all-cause mortality plus major adverse cardiovascular events. Cumulative total and event-free survival were assessed using the Kaplan-Meier survival function after stratification into skin [Na(+)] quartiles. Cox proportional hazards regression was used to model the association between skin [Na(+)] and outcomes of interest. Multiple linear regression was used to model the predictors of skin [Na(+)]. RESULTS: A total of 52 participants (42 HD and 10 PD) underwent the study procedures. The median follow-up was 529 days (interquartile range: 353-602). Increasing skin [Na(+)] quartiles were associated with significantly shorter overall and event-free survival (log-rank χ(2)(1) = 3.926, log-rank χ(2)(1) = 5.685; P for trend \textless0.05 in both instances). Skin [Na(+)] was associated with all-cause mortality \hazard ratio (HR) 4.013, [95% confidence interval (95% CI) 1.988-8.101]; P \textless 0.001\ and composite events [HR 2.332 (95% CI 1.378-3.945); P \textless 0.01], independently of age, sex, serum [Na(+)] and albumin. In multiple regression models, dialysate [Na(+)], serum albumin and congestive heart failure were significantly associated with skin [Na(+)] in HD patients (R(2) (adj) = 0.62). CONCLUSIONS: Higher skin [Na(+)] was associated with worse clinical outcomes in dialysis patients and may represent a direct therapeutic target.