SSM stands for Sisters of St. Mary, a congregation of German nuns who founded what is now SSM Health, one of the largest Catholic health systems in the United States. The name traces back to 1874, when the founding sisters were formally named after St. Mary of Victories Church in St. Louis, Missouri. Today SSM Health operates 19 hospitals and more than 60 outpatient care sites across four states, with roughly 40,000 employees.
How Five Nuns Built a Health System
SSM Health’s origins are unusually dramatic. On November 16, 1872, five German nuns led by Mother Mary Odilia Berger arrived in St. Louis with just $5 between them. They had left Germany seeking religious freedom and a chance to serve the sick. That first winter, a devastating smallpox epidemic swept through St. Louis, and the sisters went door to door begging for money, food, medicine, and supplies. Locals began calling them the “Smallpox Sisters.”
Two years later, in 1874, the group received their official name: the Sisters of St. Mary, shortened to SSM. The name came from St. Mary of Victories Church, which shared a common door with the sisters’ convent. Five years after arriving in the U.S., they borrowed $16,000 to open their first hospital, St. Mary’s Infirmary. Mother Odilia died in 1880 at age 57, just days after the Catholic Church officially recognized the congregation she founded. The health system that grew from her work now spans four states.
Where SSM Health Operates Today
SSM Health runs hospitals and clinics in Missouri, Illinois, Wisconsin, and Oklahoma. Beyond its 19 hospitals and 60-plus outpatient sites, the system includes a pharmacy benefit company, a health insurance plan, nursing homes, home care and hospice services, and two accountable care organizations. It is a not-for-profit Catholic system, meaning it operates in alignment with Catholic ethical guidelines for health care.
Some of the most prominent facilities in the network include SSM Health Saint Louis University Hospital, SSM Health Cardinal Glennon Children’s Hospital (recognized by U.S. News & World Report as a Best Children’s Hospital for 12 consecutive years), SSM Health St. Mary’s Hospital in Madison, Wisconsin, and SSM Health St. Anthony Hospital in Oklahoma City.
Clinical Services and Specialties
SSM Health covers the full range of hospital-based care: primary care, emergency services, cardiology, cancer treatment, neurosciences, orthopedics, transplant services, maternal-fetal medicine, and more. The system also runs the SSM Health Treffert Center, which specializes in diagnosing and treating autism, behavioral, and communication disorders in children and adults.
In the 2025–2026 U.S. News & World Report rankings, ten SSM Health hospitals earned recognition. SSM Health St. Mary’s Hospital in Madison, Wisconsin, stood out with a Best Regional Hospital badge and high-performing marks in 16 types of care, including heart bypass surgery, hip and knee replacement, lung cancer surgery, and stroke treatment. SSM Health St. Anthony Hospital in Oklahoma City earned high-performing ratings in areas like heart attack care, orthopedic procedures, and stroke. SSM Health Cardinal Glennon Children’s Hospital ranked nationally in seven pediatric specialties.
Catholic Identity and Community Care
As a Catholic health system, SSM Health’s mission is rooted in the values of its founding sisters: treating every person with dignity regardless of their ability to pay. The system provides charity care to patients who cannot cover their medical expenses, absorbing the cost rather than pursuing collection. In its 2024 fiscal year, SSM Health reported approximately $74.8 million in charity care costs. The system also funds community health services, health professions education, and direct charitable contributions in the regions it serves.
The “SSM” abbreviation appears across all of the system’s branding, from hospital names like SSM Health DePaul Hospital to insurance products and outpatient clinics. While the Sisters of St. Mary no longer directly manage the organization, their name and founding mission remain central to how SSM Health identifies itself more than 150 years later.