Metastasis is the major cause of cancer-related mortality. It is increasingly evident that epigenetic alterations in tumor cells enable them to overcome various barriers in this multistage process of cell spreading, and insight into the molecular roles of epigenetic regulators in tumor metastasis are just beginning to emerge. Histone demethylases appear to have critical roles in creating suitable epigenetic states for tumor cells to gain metastatic potential. These studies shed light on the roles of histone demethylases in tumor metastasis and highlight the importance of targeting these enzymes to suppress metastatic disease.