A pilot study is a small-scale, preliminary research study. For example, researchers who have discovered a new drug may first test its safety and effectiveness in a pilot study including a few dozen subjects. These individuals will be monitored closely to see if there are signs that the drug is working as anticipated and that any side effects are kept to an acceptable minimum. If pilot studies are successful, the drug must then be tested in larger-scale clinical trials and then reviewed by the FDA before it can be marketed in the US.