The group are warning that the action, which will continue until 8pm tonight has led to the cancellation of many inpatient and day-case elective procedures and hospital outpatient appointments across the country.
Routine GP testing services will be suspended for the day and while some limited services will continue wide-scale disruption to patients services cannot be avoided.
The public is being reminded to explore all other options available to them prior to attending an Emergency Department.
Over 2,100 medical scientists are stopping routine lab services in a dispute over recruitment and retention issues which they say is leading to burnout
The Union representing Medical Scientists say they have been left with no alternative as the action follows many rounds of unsuccessful talks with the HSE, Departments of Health, Public Expenditure and the Public Service Agreement Group.
If no progress is made a further two days of action are planned for May 24th and 25th with three further days of action at the end of May and start of June
