The Garyville Refinery is the 3rd largest American oil refinery with a nameplate capacity of 597,000 barrels per day (94,900 m/d). The refinery is owned and operated by Marathon Petroleum Corporation. It is located in southeastern Louisiana between New Orleans and Baton Rouge on U.S. Route 61 in Garyville, Louisiana. The facility is the newest major grassroots refinery built in the United States, located on 3,500 acres of land adjacent to the Mississippi River. The refinery is on the former San Francisco Plantation property, which was designated a National Historic Landmark in 1974.

Construction began in 1973 by ECOL, Ltd. Construction was completed in 1976, and the refinery was purchased by Marathon Oil Company. Since then, the refinery has been expanded on multiple occasions, most recently with the $3.9 billion Garyville Major Expansion (GME) Project, completed in 2009. This, along with subsequent debottlenecking, increased capacity by 234,000 barrels per day (37,200 m/d).

Garyville Refinery operations consist of crude distillation, hydrocracking, catalytic cracking, hydrotreating, catalytic reforming, alkylation, sulfur recovery, and coking. The facility primarily processes heavy sour crude oils to produce gasoline, diesel, asphalt, propylene, isobutane, propane, fuel-grade coke, and sulfur. Feedstocks are supplied via pipeline, truck, barge, rail, and ocean tanker.

The refinery employs 900 employees and 600 contract workers.

• List of oil refineries
• Marathon Petroleum Company
• San Francisco Plantation