The biomarkers are important in the Inflammatory Bowel Disease (IBD) to gain an objective measurement of disease activity and severity, as well as prognostic indicator and outcome of therapy. And they can be helpful to avoid invasive procedures. The ideal biomarker does not exist for IBD and it is likely that more than one biomarker will be needed. Biological markers potentially useful in IBD include acute-phase proteins, fecal markers, several antibodies and novel genetic determinants. The C-reactive protein (CRP) is the most studied and has been shown to be an objective marker of inflammation. CRP is a good marker of measuring disease activity in Crohn's disease (CD) and its levels can be used to guide therapy. The fecal markers (calprotectin and lactoferrin) may be helpful in differentiating patients with IBD from those with functional disorders and to predict clinical relapse. The panel of serologic markers (anti-Saccharomyces cerevisiae antibody, perinuclear anti-neutrophil cytoplasmic antibody, anti-OmpC and anti-I2 and antiglycan antibodies) for IBD can be used to stratify IBD patients into more homogeneous subgroups with respect to disease progression. Correlating serologic markers with genotypes and clinical phenotypes should enhance our understanding of the pathophysiology of IBD. The development of biomarkers in IBD will be very important in the future with the increasing utilization of novel methodological approaches like genomics and proteomics.