Introduction of biologic therapy in clinical practice represented significant progress in the treatment of inflammatory bowel diseases (IBD) because of its proven efficacy and due to the fact that biologics are the first drugs used in the treatment of IBD that can change the natural course of this diseases. At the same time, biologics are very expensive drugs with complex mechanism of action and important side effects and their use requires evidence-based clinical guidelines. These were the reasons that Referral Center of the Croatian Ministry of Health for IBD and the IBD Section of the Croatian Society of Gastroenterology organised Croatian consensus conference that defined guidelines for the treatment of IBD with anti-TNF drugs. The text below includes definitions of IBD, general principles of IBD therapy, comments on the importance of mucosal healing, analysis of reasons for nonresponse and loss of response to anti-TNF drugs, recommendation for the duration of anti-TNF therapy, rules of screening for opportunistic infections prior to anti-TNF therapy, comments on the problems with reproduction in IBD and finally guidelines for the treatment of various phenotypes of IBD including extraintestinal manifestations with anti-TNF therapy.