An update is provided on monoclonal antibodies (MAbs): concept, production, indications for the diagnosis and treatment of neoplastic diseases and autoimmune disorders, prevention of transplant rejection, and treatment of allergic diseases, autoimmune disease and other noninflammatory disorders such as coronary disease. Mention is also made of MAb use in the prevention of respiratory syncytial virus (RSV) infection. A more extensive account is provided of the use of MAb in B cell lymphomas (anti-CD20) and T cell leukemias (anti-IL-2 R). Likewise, mention is made of the use of MAbs in autoimmune disorders, such as anti-TNF-alfa in application to chronic arthritis, Crohn's disease and psoriasis, anti-C5 in the treatment of chronic arthritis, uveitis, systemic lupus erythematosus, and autoimmune hemolytic anemia. Anti-KT 3 MAb is used to treat acute rejection and graft versus host disease, while anti-IL-2 R alfa and anti-IL-2 R gamma are used for the prevention of acute transplant rejection. Anti-IgE MAb (omalizumab) is used to treat asthma and allergic rhinitis refractory to other treatments. Anti-L5 (mepolizumab), anti-IL-4, anti-TNF and anti-inflammatory cytokine mediator MAbs all have indications in asthma and severe allergic rhinitis, and in intense atopic dermatitis refractory to other treatments. As to the MAbs used for the prevention of RSV infection, mention is made of anti-epitope A of the F protein of the virus.