Medical staff are still providing emergency care but non-urgent appointments have been affected.
Members of the British Medical Association have organised the day of action in protest to pension changes.
Bosses at the Great Western Hospital say they're not expecting too much distribution and have worked closely with staff on how to reduce the impact of the strike.
Some non-urgent appointments and procedures have been postponed but if you've not been informed of any changes you should still attend your appointment.
There will be no impact on cancer treatment or inpatients.
In a statement, Dr Alf Troughton, Medical Director and Deputy Chief Executive said: "The dispute is between the government and the BMA but clearly the impact is felt at a local level. We have good working relationships with Doctors and their representatives in the Trust and we're keen for that to continue.
"The plans we have in place are designed to minimise the disruption that this strike may cause for patients and other colleagues working in the Trust. I know from our discussions with our medical colleagues they are also keen to ensure that patient safety and the quality of care provided during the day is not impacted.
"Anybody who needs emergency or urgent treatment on the day will get the care they need so shouldn't be concerned. This also applies to our patients who we have booked in for cancer treatment and those patients who will already be staying in hospital."
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