Researchers have sought therapeutic applications for monoclonal antibodies since their development in 1975. However, murine-derived monoclonal antibodies may cause an immunogenic response in human patients, reducing their therapeutic efficacy. Chimeric and humanized antibodies have been developed that are less likely to provoke an immune reaction in human patients than are murine-derived antibodies. Antibody fragments, bispecific antibodies, and antibodies produced through the use of phage display systems and genetically modified plants and animals may aid researchers in developing new uses for monoclonal antibodies in the treatment of disease. Monoclonal antibodies may have a number of promising potential therapeutic applications in the treatment of asthma, autoimmune diseases, cancer, poisoning, septicemia, substance abuse, viral infections, and other diseases.