Summary: Laboratory parameters are measured in blood (CRP, WBC, PCT, serum ECP) and stool (fecal calprotectin, fecal ECP, FOBT, GDH, in daily clinical practice to monitor the activity of inflammatory bowel diseases (IBD) and response to treatment. They are used for diagnostics, differentiation, prognosis prediction and control of the course of the exacerbation or remission phase. Despite the limitations, each laboratory indicator should be considered in the specific clinical situation for the individual patient. Identification of laboratory indicators is helpful in observing the clinical condition, including the distinction between remission and exacerbation, as well as prognosis of endoscopic activity. Symptoms, the number of bowel movements (with or without blood admixture), stool formation, endoscopic and imaging examinations together with laboratory tests are an integral element in the diagnosis and monitoring of IBD activity. The limited availability of tests and their high price may make it difficult to assess IBD activity on an outpatient basis. Research on known and new laboratory parameters expands the possibilities and development of diagnostic methods, clinical knowledge and pharmacotherapy.