Monoclonal antibodies have established therapeutic uses and some of them are contained in approved and relatively widely used medicinal products. The target structures of the activity of monoclonal antibodies vary, and for this reason monoclonal antibodies cannot be considered a uniform group in terms of their effects. For example, they are used in the treatment of tumour diseases and in patients with autoimmune conditions, which may also manifest as neurological disorders or rheumatological diseases. A number of new monoclonal antibodies are, with a view to the various possibilities of interfering with the mechanism of many diseases, also tested in clinical studies. In the Czech Republic this involves approximately hundreds of patients. In those studies where the medicine is being given to patients rather than to healthy volunteers the patients are usually not financially compensated for their participation in the study.