Doctors across Wales are due to take industrial action today over proposed pension reforms.
It's the first time this has happened since the 1970s and it means most non-emergency operations and procedures today will be cancelled.
Patients affected should already have been contacted to rearrange their appointments, but the advice for pateints who haven't heard anything is to turn up at their hospital or GP surgery as planned.
The type of appointments affected include planned operations and outpatient appointments.
Health Secretary Andrew Lansley has urged members of the British Medical Association to reconsider the planned strikes - but they say they're fighting for fairness.
However, not all doctors are supporting the action, and even where services are affected there will be emergency cover.
Patients are being advised that if they feel unwell they should make an emergency on-day appointment with their doctor - and all A&E departments and NHS Direct will be running as usual.