Introduction in the last decade the biological treatment directed against anti-TNF-α for Crohn’s disease improved the effectiveness of the therapy and at the same time increased the percentage of clinical remissions achieved. Anti-TNF-α therapies favourable affect clinical symptoms and reduce the inflammatory indices of the disease. However, the long-term biological treatment carries the risk of the loss of response and adverse events, which sometimes can be very serious. Among these agents, infliximab – a chimeric, mouse and human, monoclonal antibody, has been used in the treatment of active Crohn’s disease for the longest time. Presenting a case report of a young woman with fistualizing Crohn’s disease the authors want to share their experience and point out the therapeutic problems, which can arise during the long-term biological treatment with anti-TNF-α agents.