While arsenic has been used medicinally and as a poison for thousands of years, Fowler's solution, an arsenic compound, has had a fascinating history in medicine during the past 200 years. The use of Fowler's solution was first described and published as a treatment for malaria and syphilis in the late 1700s. Many clinical applications for Fowler's solutions have been studied and utilized over the years, but toxicities have limited its utility. Even so, arsenic trioxide, chemically related to Fowler's solution, was approved by the US Food and Drug Administration for treating acute promyelocytic leukemia. The history of Fowler's solution, its applications and uses, and benefits and risks are discussed.