Background: Anemia is an adverse prognostic marker in heart failure (HF), but its cause and relationships with other comorbidities are uncertain. Methods: All index emergency HF admissions to one urban hospital during the year 2000 were studied. Results: Of 528 consecutive admissions with HF, 45% of patients (51% men and 38% women) had anemia (Hb <13 g/dL in men and <11.5 in women), which was usually normocytic. Anemia was equally common in patients with reduced and preserved systolic function. Hematinic deficiencies were rare, but 162 (70%) of anemic patients were lymphopenic. Median (interquartile range) C-reactive protein was higher in anemic patients compared with nonanemic patients (21 [5-211] mg/L vs 13 [5-155] mg/L, P = .0086). Marked reductions in glomerular filtration rate (<30 mL/min per 1.73m2) were more common in anemic patients (24%) than nonanemic patients (9%) (P < .0001). Median follow-up was 814 days (range 632-978 days). One hundred twenty-five (54%) anemic patients died, compared with 93 (32%) nonanemic patients (P < .00001), and anemia was a predictor of death (in patients with reduced or preserved systolic function) and death or hospital readmission. Conclusions: Renal dysfunction is one probable cause of anemia in HF. The overlap of anemia and lymphopenia suggest that hematopoiesis may be more generally depressed. Anemia is a predictor of adverse outcome in HF, irrespective of systolic function.