Calprotectin is a calcium-binding protein found in neutrophils. Increased levels are found in stools after mucosal damage due to inflammation, which causes influx of neutrophils into the gut lumen.This article is based on a review of the most pertinent publications found on Medline and our clinical experience from more than 10 years of using the test.Calprotectin is primarily a marker of intestinal inflammation. The test is therefore a useful tool for investigation of abdominal discomfort. At diagnosis all patients with inflammatory bowel disease will have clearly elevated values of faecal calprotectin. On the other hand, in patients with irritable bowel syndrome the levels are normal. Normalization of faecal calprotectin seems to be a strong indicator of mucosal healing.Correct use of the test can therefore contribute to reducing the number of unnecessary colonoscopies, which is especially important in children. Faecal calprotectin is a simple test and an objective parameter of inflammatory disease activity which is useful for assessment of disease course and monitoring of response to medical treatment in patients with inflammatory bowel disease.