Anaemia is the most common extraintestinal complication of inflammatory bowel diseases in both hospitalised and outpatient patients. Symptoms associated directly with reduced haemoglobin levels as well as the consequences of iron, vitamin B₁₂ or folic acid deficiency significantly impair the quality of life. Memory disorders and difficulty focusing, depression or mood swings are just some of the symptoms that can be a consequence of undiagnosed and untreated anaemia. Determination of the aetiology of anaemia in inflammatory bowel diseases, which may result not only from gastrointestinal bleeding, is important in choosing an appropriate treatment regimen. Proper diagnosis and monitoring are important in the prevention and diagnosis of anaemia. Choosing the right treatment method is the key element. Decisions regarding the use of oral or intravenous iron forms should be justified and applicable in everyday practice. The goal to be achieved is effective treatment of anaemia, which translates into improved quality of life of patients with inflammatory bowel disease. Improved comfort of life, which is so important for these patients, may be achieved regardless of the clinical activity of the underlying disease. Furthermore, proper treatment of anaemia optimises the therapy, reducing the frequency of hospitalisations and blood transfusions and, consequently, the total cost of treatment.