Is chemotherapy used to treat a condition other than cancer?

Yes: Methotrexate is a chemotherapeutic agent that has been used for many years to treat rheumatoid arthritis (although at a lower dose than used to treat cancers). Paclitaxel is a drug used to treat breast and ovarian cancer; it is also one of the drugs used in drug-eluting stents for treatment of coronary artery disease.

Yes: A few chemotherapy also have been used in different conditions other than cancer for instance- Methotrexate is given for rheumatological disease and other autoimmune problems, 6mp is given for colitis ( crohns disease, ulcerative colitis); Rituxan (rituximab) is given for some autoimmune condition.