Drug repurposing, the strategy of using drugs developed for one disease to treat a different one, is rapidly gaining attention in oncology. The idea of using non-cancer drugs as new cancer treatments is a challenging one - but it holds great promise. However, there are many factors involved in this strategy, and evidence in support of it comes from many sources. A recent special theme on drug repurposing in Frontiers in Medicine and Frontiers in Pharmacology included 8 articles addressing these various issues. This editorial outlines the articles and puts into context the many streams of activity involved in repurposing in oncology.