A Nursing Agency (also known as Nurses Agency or Nurses Registry) is a business that provides nurses and usually health care assistants (such as Certified Nursing Assistants) to people who need the services of healthcare professionals. Nurses are normally engaged by the agency on temporary contracts and make themselves available for hire by hospitals, care homes and other providers of care for help during busy periods or to cover for staff absences. Some nurses may be seconded to private clients who choose to receive their nursing care within their own homes. English nursing agencies are regulated by the Commission for Social Care Inspection.

In the United States, they are also called Nurse Registries. It is a staffing agency which may provide per diem or locum tenens nursing personnel to hospitals, medical offices and individuals. They are generally small, privately owned businesses. They are also known as "nursing pools" and "nursing staffing agencies".

As with other staffing agencies, a large amount of capital is necessary to operate, since nurses must be paid by the registry as often as they work, but the hospital or other institution utilizing the services of the registry might not pay the registry until several months after the work has been done. Profit margins for this type of business go between 4% and 70%.

Nurse staffing is a seasonal business. During holidays, hospitals often pay their staff overtime pay, and thus the need for external staffing services is diminished. An opposite effect is felt during summer time vacations, when staff employees at hospitals take time off and the services of the nurse registry are in greater need.

Nurse staffing is very demanding and requires a high degree of care and responsibility. There are many liability issues which must be kept in mind. Claims of negligence and inappropriate actions by the registry's nurses may result in lawsuits over bodily injury. Malpractice insurance must be carried by the registry.