Many medications used off-label are inexpensive, but many others, in particular biotechnology drugs, are costly. Biotechnology drugs are defined by the industry as biopharmaceuticals, such as monoclonal antibodies, recombinant enzymes, and cytokines, which are produced using cellular or molecular processes, as well as more traditional small-molecule drugs, which are manufactured chemically but target a biological process (6). These drugs were developed to treat relatively rare diseases but are now being used for a host of other conditions, despite their high cost. Of the 250 distinct biotechnology drugs in use as of 2007, 94 (37.6%) are single-use products, such as imaging agents or vaccines (7). Of the remaining 156 drugs, 65 (41.6%) cost at least $1000 per month according to price information from multiple online domestic pharmacies and reports of new drug releases in major newspapers. Leading the list of expensive biotechnology agents are chemotherapeutic drugs (36.9%), followed by enzyme-deficiency drugs (18.5%); anti-infectious agents, dermatologics, and rheumatologics together make up another 21.6% of the total (Table 1). Whereas the drugs used for orphan diseases, such as congenital enzyme deficiency disorders, have no off-label uses, chemotherapeutic agents are used for types of cancer other than those for which they have been tested and approved. Many of the rheumatologics are used off-label for dermatologic conditions (8), and the pulmonary vasodilators are used for rheumatoid arthritis and inflammatory bowel disease (Table 2).