INTRODUCTION: Few studies have investigated the association between level of social deprivation and acute hospital outcome for admissions to adult general critical care units. It is important to be aware if an association exists because risk prediction models do not adjust for deprivation. MATERIALS AND METHODS: Deprivation was measured using the Index of Multiple Deprivation (IMD) 2004, developed using 2001 census data in England. Eighty-four thousand four hundred twenty-three admissions to 138 adult general critical care units in England were selected from the Case Mix Programme Database from 1 year before to 1 year after the census date and linked to the IMD using postcodes. Logistic regression analysis was used to investigate a possible association between quintile of IMD and acute hospital mortality. RESULTS: As deprivation increased, acute hospital mortality also increased (P < .001). This association remained after adjusting for age, sex, acute severity, medial history, source of admission, and reason for admission to critical care (adjusted odds ratio for most vs least deprived quintile, 1.19; 95% confidence interval, 1.10-1.28). CONCLUSIONS: There is an association between increasing deprivation and increasing risk of mortality for admissions to adult general critical care unit units in England. Further research is required to identify other unmeasured potential confounders (eg, smoking, alcohol consumption) as possible explanations for this association.