BACKGROUND There is no previously published epidemiological study exploring the association between red blood cell distribution width (RDW) and mortality in patients with cardiogenic shock (CS). The aim of this study was to examine the association between RDW and the risk of all-cause mortality in these patients. MATERIAL AND METHODS We analyzed clinical data from the MIMIC-III V1.4 database. We collected data on each patient's demographic parameters, vital signs, laboratory parameters, vital signs, comorbidities, and scoring systems on ICU admission. Cox proportional hazards models were used to assess the association between RDW levels and the 30-day, 90-day, and 365-day mortality in patients with CS. RESULTS There were 1131 patients meeting inclusion criteria in our study. In multivariate analysis, following adjustment for age, sex, and ethnicity, higher RDW in tertiles and quintiles were all associated with increased risk of 30-day, 90-day, and 365-day all-cause mortality. Furthermore, after adjusting for more relevant confounders, RDW remained a significant predictor of risk of 30-day, 90-day, and 365-day mortality (tertile 3 versus tertile 1: HR, 95% CI: 1.66, 1.19-2.31; 1.73, 1.28-2.33; 1.80, 1.38-2.34). Similarly significant robust associations were found in RDW levels stratified by quintiles. CONCLUSIONS Higher RDW is associated with increased risk of all-cause mortality in critically ill patients with CS.