The Medical Services function of the Health Care Agency provides for emergency care and essential medical services to persons for whom the county has responsibility, by law.

California Children's Services (CCS) is a statewide program managed by the California Department of Health Care Services (DHCS). CCS specializes in medical care, case management, physical/occupational therapy and financial assistance for children with certain health care needs.

The Health Disaster Management (HDM) division structures the Agency's emergency response functions related to all-hazards planning, including bioterrorism, pandemic influenza, natural disasters, the county-wide 9-1-1 system for medical emergencies, and other County health-related disasters. HDM includes:

Emergency Medical Services (EMS) which regulates, monitors, plans, and coordinates pre-hospital emergency medical services, hospital emergency programs, and trauma centers.

Disaster Preparedness and Training participates in and supports ongoing all-hazards planning and preparation activities undertaken by the Orange County Operational Area (OA) and is responsible for coordinating organized planning efforts with County departments, local cities and special districts to mitigate, prepare for, respond to, and recover from disasters.

Medical Reserve Corps (MRC) who's mission is to enhance the emergency preparedness and response capabilities of Orange County through advanced registration, organization and training of volunteer health professionals who can be readily mobilized to respond to a major emergency or disaster, whether man-made or natural, when the existing health infrastructure is overwhelmed and unable to provide needed medical care in a timely manner.

The Medical Services Initiative (MSI) division of the Medical Services function administers various payment programs for indigent medical services, entirely through contracts with private medical providers.