Recently there has been increased interest in microdosing LSD, that is, using doses of LSD that are not psychoactive (typically 10 micrograms). A standard recommendation is microdosing every three days. The basic idea derives from earlier studies of psychoactive doses of LSD or other psychedelics such as mescaline, where suggestions were made that the doses helped improve creativity. For years, we at Heffter have been interested in and have helped develop the scientific evidence related to the value of psychedelics. Given the increased interest in microdosing, it is worth exploring what we know and don't know on the topic, particularly given that LSD is a Schedule 1 drug and that possession even of a microdose is illegal.