Dr. Orna O'Toole completed her undergraduate training in University College, Dublin (UCD), achieving both a medical degree (MD) and bachelor of science (BSc) concurrently.  

During her Senior House Officer (SHO) training scheme at the Mater Misericordiae University Hospital, Dublin she spent time at the Cleveland Clinic, Ohio, USA during which time she developed an interest in neurology.  After successfully completing her membership of the Royal College of Physicians of Ireland, her neurology training was undertaken in Ireland as part of the national neurology training scheme.  Dr. O'Toole completed three years additional research in Beaumont Hospital, Dublin culminating in an MD in the Epidemiology of Motor Neuron Disease in Ireland.

Later, having spent time as a temporary consultant in both Cork University Hospital and the Mater Misericordiae University Hospital, Dr. O'Toole travelled to the Mayo Clinic, Minnesota, USA to undertake a fellowship in autoimmune neurology before returning to Ireland to take up her post here at Mercy University Hospital.