A triad of symptoms characterises Felty's syndrome: seropositive rheumatoid arthritis (RA), splenomegaly and neutropenia. The treatment of Felty's syndrome is based on using classic synthetic and biological disease-modifying drugs (DMARDs). In this article, we present a case of a patient with Felty's syndrome who was treated with biologic treatment. A systematic search of the literature on the electronic medical database was conducted. The drugs from the DMARD group, despite reducing the activity of the disease, may cause significant clinical complications. It is important to know about the diagnosis, differentiation and treatment of neutropenia and the prevention of febrile neutropenia. The article discusses the current therapeutic possibilities using both classical and biologic DMARDs.