Both an international and regional referral center, Beth Israel Deaconess Medical Center (BIDMC) in Boston, Massachusetts is a major teaching hospital of Harvard Medical School. It was formed out of the 1996 merger of Beth Israel Hospital (founded in 1916) and New England Deaconess Hospital (founded in 1896). Among independent teaching hospitals, Beth Israel Deaconess Medical Center is the third-largest recipient of biomedical research funding from the National Institutes of Health. Research funding totals nearly $150 million annually. BIDMC researchers run more than 1,000 active sponsored projects and 200 clinical trials. The Harvard-Thorndike General Clinical Research Center, the nation's oldest clinical research laboratory, has been located on this site since 1973. BIDMC is equally known for its outstanding, compassionate patient care, through a multidisciplinary effort from outstanding physicians, nurses, physical therapists, pharmacists and social workers. It is considered a national leader in multiple clinical and research areas, including cardiovascular, renal, liver, pancreas, gastric motility, infectious disease, women's health, diabetes, cancer and minimally invasive surgery. The information technology services are among the best in the nation, from the cutting edge emergency room electronic dashboard to the integrated Web Online Medical Record. The surgical and procedural simulation center is a national model of excellence.

Located in the Longwood Medical and Academic Area, BIDMC is the flagship hospital of the Caregroup Healthcare System of Massachusetts and is consistently ranked as one of the best hospitals in the US in by U.S. News & World Report. It is one of the largest hospitals in New England, surpassed only by Massachusetts General Hospital and Brigham and Women's Hospital, both also in Boston.

The President of BIDMC is Paul Levy, who assumed the role in late 2001.

Notable milestones in the history of medicine at Beth Israel Deaconess include:

• The first administration of insulin in New England occurred at Deaconess Hospital in 1922.
• The first implantable cardiac pacemaker was developed at Beth Israel Hospital in 1960.
• The first Rights of Patients statement in the nation implemented at Beth Israel Hospital in 1972 .
• Vascular endothelial growth factor (VEGF), is discovered at Beth Israel Hospital in 1983.
• The first successful liver transplant in New England was performed at the Deaconess Hospital in 1983.
• The first baby conceived through in vitro fertilization in Massachusetts was delivered at Beth Israel Hospital in 1986.
• The first evidence that abnormalities in the visual system of the brain could help explain problems of people with dyslexia was discovered by Beth Israel researchers in 1991.
• New England's first minimally invasive coronary bypass surgery was performed at Deaconess Hospital in 1995.
• The first deep brain stimulator implantation for the treatment of Parkinson's disease in New England was performed at Deaconess Hospital in 1995.
• BIDMC performed the first adult live-donor liver transplant in New England in 1998.
• A patent was issued in 1998 for the Cohn cardiac stabilizer, developed by BIDMC cardiothoracic surgeon William Cohn, M.D., allowing coronary artery bypass surgery to be performed without the use of a heart-lung machine.
• BIDMC became the only clinical trial site in Boston to test a new therapeutic AIDS vaccine on normal, healthy adults in 2002.
• In 2003, BIDMC joined a select list of hospitals nationally conducting the first clinical trial of the AbioCor® Implantable Replacement Heart.
• In 2003, BIDMC researchers identified the source of preeclampsia , a life-threatening complication of pregnancy and one of the leading causes of maternal and infant mortality worldwide.

Beth Israel Deaconess Medical Center sponsors numerous post-graduate medical residency programs in a variety of medical subspecialties including internal medicine, surgery, pathology, neurology and radiology.