Ulcerative colitis represents a chronic condition occurring in relapsing and remitting fashion with uncertain outcome and requires lifelong treatment with considerable side effects. Diagnostic methods currently in use, clinical (endoscopy), imaging (CT, MR) or laboratory (C - reactive protein, calprotectin) give an insight into disease activity, but are possibly associated with significant discomfort for the patient and / or increased risk of irradiation and potential allergic reactions on contrast agents. For that reason there is a need for a noninvasive, biologically inert method for evaluation of disease activity in inflammatory bowel disease (IBD). Thermography possesses most of these characteristics. The aim of this study is to find potential link between pathological thermographic signs and endoscopic findings, serum C reactive protein (CRP) and calprotectin in the stool of patients with active and extensive ulcerative colitis.