Massachusetts General Hospital is the original and largest teaching hospital of Harvard Medical School, Harvard University located in the West End neighborhood of Boston, Massachusetts. Massachusetts General Hospital houses the world's largest hospital-based research program, the Mass General Research Institute, with an annual research budget of more than $1.2 billion in 2021. It is the third-oldest general hospital in the United States with a patient capacity of 999 beds. Along with Brigham and Women's Hospital, Mass General is a founding member of Mass General Brigham, formerly known as Partners HealthCare, the largest healthcare provider in Massachusetts.

A teaching hospital is a hospital or medical center that provides medical education and training to future and current health professionals. Teaching hospitals are almost always affiliated with one or more universities and are often co-located with medical schools.