The rally following the walkout by porters at Ninewells and Royal Victoria hospitals.
Porters at Ninewells and Royal Victoria hospitals began strike action over pay.
As many as 120 took part in a mass walkout at 1pm on Friday in the first full industrial action of the dispute.
Workers formed a picket line outside Ninewells.
Porters began offering reduced services on Wednesday, and strike action is to continue with activists working half days on Monday and Friday for the next fortnight, or until the payment issues under dispute are resolved.
Both Unite and NHS Tayside claim the strike action will not affect patient services.
Talks between porters and the health organisation were ongoing yesterday but no agreement has yet been reached.
Union bosses contend porters at Ninewells and Royal Victoria are on a lower pay grade than colleagues at other hospitals in the NHS Tayside area.
Bosses have criticised the union for failing to abide by findings of an internal review in which NHS Tayside found that pay was fair.
The union claims its own investigations have discovered the porters should be on higher pay bands. Unite has been threatening industrial action since last summer.
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