Even in the era of primary percutaneous coronary intervention (PCI) in patients with ST-segment elevation myocardial infarction (STEMI) complicated by cardiogenic shock (CS), mortality remains high. Whether admission hemoglobin (Hb) concentration is a predictor of mortality in patients with CS treated with primary PCI is unexplored. We assessed the relation between admission Hb concentration and 1-year mortality in patients with STEMI and CS who were treated with PCI at admission. We investigated a cohort of 265 patients with STEMI with CS on admission. Patients were categorized in 3 groups according to plasma Hb levels at admission: 9.6 g/dl (group I, n = 22), 9.6 to 12 g/dl (group II, n = 59), and >12 g/dl (group III, n = 184). All-cause mortality at 1 year was 64%, 46%, and 35% for groups I, II, and III, respectively (p = 0.007). Multivariate logistic regression analysis showed that the odds for mortality increased 17% for every 1.0 g/dl decrease in plasma Hb (odds ratio 1.17, 95% confidence interval 1.01 to 1.35, p = 0.042). In conclusion, admission Hb concentration is an independent predictor for 1-year mortality in patients with STEMI undergoing primary PCI.