Of 6,929 consecutive patients who were treated with percutaneous coronary intervention, 1,708 (24.6%) had anemia according to criteria of the World Health Organization. Compared with patients who did not have anemia, those who did have anemia were older, more frequently women and African-American, had a smaller body mass index, and higher frequencies of cardiovascular risk factors and co-morbid conditions. Patients who had anemia compared with those who did not have anemia had significantly (p <0.0001) higher mortality rates during hospitalization (1.9% vs 0.4%) and at 1 year (12.8% vs 3.5%). After adjustment for potential confounders, baseline hematocrit remained a significant predictor of a 1-year mortality rate (hazard ratio 0.93 per 1% increase in hematocrit, 95% confidence interval 0.91 to 0.95).