The Don Mariano Marcos Memorial State University (DMMMSU) is the state university system in the province of La Union in the Philippines. It was established in 1981 by former president Ferdinand Marcos through Presidential Decree 1778, combining various state-run schools in La Union. Like Mariano Marcos State University in Ilocos Norte, it is named after the former president's father, Mariano Marcos.

Before 1993, DMMMSU had seven campuses across the province. After a reorganization, these campuses were grouped into four autonomous units: North La Union Main Campus (DMMMSU-NLUC), Mid La Union Campus (DMMMSU-MLUC), South La Union Campus (DMMMSU-SLUC), and the Open University System (DMMMSU-OU). Each unit is led by a chancellor/director, and the entire system is headed by the university president, Dr. Jaime I. Manuel Jr.

The North La Union campus, created in 1993, houses DMMMSU's central administration. It originated from the College of Agriculture and Forestry (CAF), Institute of Veterinary Medicine (IVM), Institute of Computer Studies (ICS), and Institute of Environmental Studies (IES). In 2002, the College of Agriculture and Forestry split into the College of Agriculture and the Institute of Agroforestry and Watershed Management (IAWM). Notably, the Bacnotan Campus hosts national research institutes like the Sericulture Research and Development Institute (SRDI) and the National Apiculture Research Training and Development Institute (NARTDI).