[5] Several medical specialties were founded at the hospital, including neurosurgery by Harvey Cushing and Walter Dandy, cardiac surgery by Alfred Blalock and Vivien Thomas,[6] and child psychiatry by Leo Kanner.

A year prior to his death, he sent each a letter telling them that he was giving "thirteen acres of land, situated in the city of Baltimore, and bounded by Broadway, Wolfe, Monument, and Jefferson streets upon which I desire you to erect a hospital."

"[13] Hopkins instructed the trustees to "bear constantly in mind that it is my wish and purpose that the hospital shall ultimately form a part of the Medical School of that university for which I have made ample provision in my will."

[14] When completed in 1889 at a cost of $2,050,000 (US$50.8 million in 2022[11]), the hospital included what was then state-of-the-art concepts in heating and ventilation to check the spread of disease.

[16] The decision to begin coeducation was a result of a shortage of funds, as the Baltimore and Ohio Railroad stock that was supposed to cover cost was used up in building the hospital in 1889 and the medical school had not yet been built.

After several discussions, the trustees agreed to their terms and accepted the financial help of these four women with only one of the doctors, William H. Welch, resisting.

"[15] Halsted, the first chief of the Department of Surgery, established many other medical and surgical achievements at Johns Hopkins including modern surgical principles of control of bleeding, accurate anatomical dissection, complete sterility, and the first radical mastectomy for breast cancer (before this time, such a diagnosis was a virtual death sentence).

His other achievements included the introduction of the surgical glove and advances in thyroid, biliary tree, hernia, intestinal and arterial aneurysm surgeries.

He created new surgical approaches to women's diseases and invented numerous medical devices, including a urinary cystoscope.

[15] A notable sight at the hospital is the marble statue Christus, a Carrara marble statue in the Billings Administration Building rotunda of the resurrected Jesus based on the 1833 original by Bertel Thorvaldsen, which was a gift by Baltimore merchant William Wallace Spence; it is a replica of the original by Danish sculptor Bertel Thorwaldsen in Copenhagen.

Eventually treating over 60,000 children a year, the Harriet Lane Home became a pioneer treatment, teaching, and research clinic, and the first to have subspecialties in pediatrics as created by Edwards A.

Wilmer received a medical degree from the University of Virginia School of Medicine in 1885 and later worked in New York City, Washington D.C., and Baltimore, where he established the institute.

Lawson Wilkins established an endocrine clinic that developed procedures used universally to treat children with certain glandular disorders, including dwarfism.

John E. Bordley and William G. Hardy made strides in detecting hearing impairments in very young children.

Other accomplishments of the hospital include the development of HeLa by George Otto Gey, head of tissue culture research in 1951,[29] the first and arguably most important line of human cells grown in culture, identification of the three types of polio virus, and the first "blue baby" operation, which was done by surgeon Alfred Blalock in collaboration with Helen Taussig, a Hopkins graduate specializing in pediatric cardiology and surgical technician Vivien Thomas that opened the way to modern cardiac surgery.

[34] In May, 2019, the hospital completed an $80 million expansion project at its Green Spring Station campus in Brooklandville, Maryland, offering out-patient surgery, imaging, and oncology treatment at the 3-story, 100,000-square-foot (9,300 m2) Pavilion III.

The hospital provides comprehensive pediatric specialties and subspecialties to infants, children, teens, and young adults aged 0–21[39][40][41] throughout Baltimore and the wider United States.