Abstract Acute kidney injury (AKI) is a common disorder that complicates the hospital course of many patients. AKI is linked with an independent risk of death, hospital length of stay and chronic kidney disease (CKD). Several preoperative predictors are found to be associated with AKI after surgery independent of its origin (cardiac versus non-cardiac). Among these, anaemia has been widely recognized and studied. Anaemia is more common within the surgical population for various reasons (iron deficiency, blood loss, anaemia of chronic disease such as inflammatory state, malignancy or CKD). Both pre- and postoperative anaemia have a deleterious impact on different clinical outcomes including AKI. In this issue, Nishimoto et al. investigated whether AKI could be a risk factor for anaemia (and not the opposite) and whether anaemia could be an independent mediator of mortality after AKI.