The class of immunosuppressive drugs is heterogeneous and contains drugs with different mechanisms of action and different profile of side effects. The profile of the immunosuppressive effect also differs: some drugs more or less evenly suppress all types of immunity, others have particular selectivity in relation to transplant immunity and autoimmunity, with a relatively smaller effect on antibacterial, antiviral and antitumor immunity. Examples of such relatively selective immunosuppressants are thymodepressin, cyclosporin A and tacrolimus. Immunosuppressive drugs differ in their primary effect on cellular or humoral immunity.