Antimetabolites are a group of drugs that inhibit the metabolism of normal cells, thus selectively killing cancerous cells. These drugs are used in chemotherapy and are considered as one of the most effective ways to treat cancers. There are several synonyms for antimetabolites, including antifolates, folate analogs, pyrimidine analogs, and purine analogs. Folate analogs work by inhibiting the enzyme dihydrofolate reductase, which is essential for the synthesis of DNA. Pyrimidine analogs and purine analogs work by inhibiting the enzymes that are involved in the synthesis of nucleic acids, which are essential for cell division. Antimetabolites can be used alone or in combination with other chemotherapy drugs to increase their effectiveness.