Mary J. Ruwart (born October 16, 1949) is an American retired biomedical researcher and a libertarian speaker, writer, and activist.

After a 2½ year term on the faculty of the Department of Surgery at Saint Louis University School of Medicine, Ruwart spent 19 years as a pharmaceutical research scientist for Upjohn Pharmaceuticals, and has written extensively on the subjects of government regulation of the drug industry and on libertarian communication.

[2] Ruwart was the Libertarian Party of Texas's nominee for U.S. Senate in 2000, where she faced incumbent Republican Kay Bailey Hutchison; Ruwart polled 1.16% of the popular vote (72,798 votes), finishing fourth of four candidates behind Green Party candidate Douglas Sandage.

[citation needed] In 2002, libertarians launched an unsuccessful lobbying campaign to get Dr. Ruwart appointed Food and Drug Administration (FDA) Commissioner.

[citation needed] Additionally, Ruwart has served on the boards of the International Society for Individual Liberty, the Fully Informed Jury Association, and the Michigan chapter of the Heartland Institute.