Chronic obstructive pulmonary disease (COPD) is one of the most prevalent chronic diseases, with an increasing rate in morbidity and mortality. In recent years, there has been a greater awareness about the clinical importance of systemic effects and other chronic conditions associated with COPD, as these significantly impact on the course of disease. The most studied extrapulmonary manifestations in COPD include the presence of concomitant cardiovascular disease, skeletal muscle wasting, osteoporosis and lung cancer. Anaemia is a recognised independent marker of mortality in several chronic diseases. Recent studies have shown that anaemia in patients with COPD may be more frequent than expected, with a prevalence ranging from 5% to 33%. Some evidence suggests that systemic inflammation may play an important pathogenic role, but anaemia in COPD is probably multifactorial and may be caused by others factors, such as concealed chronic renal failure, decreased androgenic levels, iron depletion, angiotensin-converting enzyme inhibitor treatment and exacerbations. Low levels of haemoglobin and haematocrit in COPD patients have been associated with poor clinical and functional outcomes as well as with mortality and increased healthcare costs. Despite the potential clinical benefit of successfully treating anaemia in these patients, evidence supporting the importance of its correction on the prognosis of COPD is uncertain. © 2013 John Wiley & Sons Ltd.