Purposes: To explore the association of anaemia with risk of outcomes of in-hospital patients with acute myocardial infarction (AMI) and atrial fibrillation (AF). Methods: Patients with AF and AMI at their first hospitalizations in three hospitals (Beijing Tongren Hospital, Beijing Friendship Hospital, Capital Medical University and China-Japan Friendship Hospital) were retrospectively reviewed and divided into two groups (with vs. without anaemia) according to haemoglobin within one day before or after admission. Results: 864 patients with AF and AMI (mean age:74.22 years; 39.9% female) were included in the current study. Patients with anaemia had increased risk of any bleeding (adjusted OR: 2.29, 95% CI: 1.43-3.68, p = 0.001), minor bleeding (adjusted OR: 2.37, 95% CI:1.40-4.01, p = 0.001), gastrointestinal bleeding (adjusted OR: 2.53, 95% CI:1.51-4.25, p < 0.001) and other death causes (adjusted OR: 1.71, 95% CI: 1.07-2.72, p = 0.02) compared to those without anaemia according to logistic regression. However, there was no difference in the risk of stroke or/and systematic embolism (SE) between patients with and without anaemia. Conclusions: In the Chinese in-hospital AMI and AF cohort, anaemia was shown to be associated with increased risk of any bleeding, minor bleeding, gastrointestinal bleeding and other death causes, but not the risk of stroke or/and SE.