Medical records evolved as part of the development of modern medicine in the late 19th and early 20the century. Medical records started as simple notes to remind physicians who their patients were, what they had been seen for, and what has been prescribed for them. There was no team care and few patients went to hospital. Physicians saw relatively few patients and would see the same patients for years, making it less important to record every detail of the encounter. There was also much less to record because there were few diagnostic tests and a limited pharmacy. Even if a patient were admitted to hospital, hospitals provided nursing, custodial, food, and hotel services, not modern day medical services. Nursing was low- technology patient care. What laboratory work that was performed was often done by the physician. The nurses, often nuns, were available night and day and knew the patient’s condition and needs. Medical records served as documentation but were not a primary vehicle for communication between medical care providers. Simple narrative reporting was used because there were few events to record and little need for retrieving information from the record.

Medical records were kept as much for business purposes as for medical care. They were used to make out bills and to allow the physician to send letters to patients if he were to move his practice. There was no medical insurance so there was no reason to share medical information with anyone else. The records might be transferred to another physician if the physician died or went out of practice. Patient access to records was not an issue, both because the records were so limited and because there was little occasion for patients to need access for insurance or legal purposes. The law assumed that medical records were simply business records that belonged to the physician, just as the records of clothes cleaned belong to the dry cleaner and the inventory records belonged to the general store owner. The patient's interest in the information in the records was not recognized until much later.

Privacy depended on the physician's professional ethics. Physicians were expected to keep their patient's confidences. A physician with a reputation for violating his patient's privacy could expect to lose business, but patients had little legal recourse. This expectation of privacy was not absolute. Physicians were required to report persons with communicable diseases to the public health authorities, who would investigate cases and might quarantine the reported individuals. Privacy was not an important issue because medical records were so limited (outside of psychiatry) and because there were few pressures to release records. Since the records were paper in file cabinets, there was little chance for inadvertent rerelease. While the Eagleton affair showed that record privacy could be breached in extreme cases, there was little risk to most patients.