Abstract: Antimitotic agents have been the most successful pharmacological agents for the treatment of cancer. The term "antimitotic agent" has traditionally been synonymous with tubulin-targeting compounds, but as a consequence of the large number of new compounds and mechanisms that have been identified recently, a much broader definition is currently needed. This review attempts to provide a broad overview of compounds and their cognate protein targets which result in a block in mitosis. Focus has been placed on agents that act directly on the mitotic machinery rather than on targets further upstream such as growth factor receptors.