The inflammation is an important component of the bowel wall structure. The amount of inflammation is gradually increased from normal state, to functional bowel disorders and to inflammatory bowel disease. Calprotectin is a recently established marker for intestinal inflammation. This paper surveys the present knowledge on fecal calprotectin testing as predictor of intestinal inflammation. We also show on a sample of patients that inflammation as tested with fecal calprotectin test may also be found, in lower degree, in irritable bowel syndrome. In inflammatory bowel disease, the calprotectin fecal test shows higher intensity values.