Dendritic cells are one of the major populations of immune cells. Due to the presence of specific receptors dendritic cells (DCs) are able to respond to both intra- and extracellular antigens. The diversity of this cell population is a result of differences in localization, stage of maturation, phenotype and function. In recent years there has been a shift in perception of DCs not only as inducers of immune reactivity but also as crucial regulators of immunity, which include ability to induce and maintain tolerance and also as effector cells, which are capable to kill tumor cells (NKDCs). Scientists around the world are analyzing the role of DCs in generation, maintenance or inhibition of pathological conditions, such as: tumors, autoimmune diseases or graft rejection. Highly developed research are focused on generating and modulating the activity as well as genetic modifications of DCs. All knowledge obtained in those research may contribute to the acceleration of DC-based therapies in clinics. Mimicking natural properties of pathogen structural elements (i.e. bacterial cell wall), that induce immune response, scientists try to design safer and more effective analogs (MDP, MB, CpG-ODN) to use them to improve health condition in patients with defective immune system reactivity.