Discharge anaemia is common following acute coronary syndromes (ACS). However, it is unknown if chronic anaemia (CA) and hospital-acquired anaemia (HAA) are associated with similar outcomes. In this retrospective analysis of 4083 ACS admissions treated with percutaneous coronary intervention in Switzerland (SPUM-ACS registry), 1896 patients (46.4%) had discharge anaemia (CA: n = 643 (15.7%) vs. HAA: n = 1253 (30.7%)). Landmark analysis that matched patients with CA (n = 504) and HAA (n = 866) with non-anaemic patients found increased 1-year major adverse cardiovascular events (cardiovascular mortality, myocardial infarction, stroke) among patients with CA (6.9% vs. 3.0%, HR 2.073, 95% CI 1.039-4.134, p = 0.039) and HAA (3.8% vs. 2.3%, HR 1.772, 95% CI 1.002-3.232, p = 0.049). Only CA was associated with increased 1-year all-cause mortality (7.9% vs. 1.6%, HR 4.255, 95% CI 1.950-9.284, p < 0.001). CA and HAA were associated with poor 1-year cardiovascular outcomes. Only CA was associated with increased all-cause mortality suggesting that HAA and CA represent distinct subclinical entities.