Iron deficiency, defined as ferritin <100 µg/L or ferritin 100-299 µg/L if the transferrin saturation is <20 %, with or without anaemia is a common comorbidity in patients with acute and chronic heart failure. International and Swedish guidelines recommend treatment of iron deficiency with intravenous iron in patients with symptomatic heart failure and ejection fraction <50 %. Controlled studies document positive effects from treatment with iron carboxymaltose on symptoms, quality of life, functional parameters and risk of hospitalisation. We present a simple algoritm based on published data to help the responsible physician to manage these patients in clinical practice.