Drug repurposing is a cost-effective and rapid alternative to identify new drugs. Drugs have already met with FDA approval allowing the early stages of drug development to be bypassed. By mining repurposed drug libraries for new indications, researchers can rapidly move to the clinical testing portion of the drug discovery process. This approach dramatically shortens the development timeline and gets new treatments to patients faster. With new technologies and approaches, including in vivo zebrafish-based screening, drug repurposing has become more streamlined and less accidental than it was in the past. By using a more systematic approach, existing compounds are being tested for both common and rare diseases faster and with greater success.