Mary Landrieu

Treasurer of LouisianaIn office
January 1, 1988 – January 8, 1996GovernorEdwin Edwards
Buddy RoemerPreceded byMary Evelyn ParkerSucceeded byKen DuncanMember of the Louisiana House of Representatives
from the 90th districtIn office
January 1980 – January 1, 1988Preceded byClyde F. Bel Jr.Succeeded byMitch LandrieuPersonal detailsBornMary Loretta Landrieu
(1955-11-23) November 23, 1955
PartyDemocraticSpouseChildren2ParentMoon Landrieu (father)RelativesMitch Landrieu (brother)EducationLouisiana State University (BA)Signature

Mary Loretta Landrieu ( ; born November 23, 1955) is an American entrepreneur and politician who served as a United States senator from Louisiana from 1997 to 2015. A member of the Democratic Party, Landrieu served as the Louisiana State Treasurer from 1988 to 1996, and in the Louisiana House of Representatives from 1980 to 1988.

Landrieu came to national attention in the wake of Hurricane Katrina in 2005 after she publicly criticized the federal response to the natural disaster. Her opposition to the public option played a major role in the crafting of the 2010 Affordable Care Act, since she did not agree to support it until additional concessions were granted to support Louisiana's Medicaid system. In 2011, she became a cardinal (chair) of the Senate's Homeland Security Appropriations Subcommittee. She chaired the Senate Committee on Small Business and Entrepreneurship from 2009 to 2014, and chaired the Senate Committee on Energy and Natural Resources from 2014 to 2015.

Landrieu was defeated in her 2014 re-election campaign by Republican Bill Cassidy, with Cassidy triumphing in a runoff. As of 2026, Landrieu is the most recent Democrat to serve in the U.S. Senate from Louisiana.