Affected workers from the New Zealand Educational Institute, the Service and Food Workers Union (SFWU) and the Public Service Association will march from Dunedin Hospital to the Octagon and gather there between 12.30pm and 1.30pm.
Rallies are planned in 27 centres nationally, and in Otago several hundred workers could be involved.
All three unions are concerned their members, some of whom are paid as little as $12.94 an hour, are facing a wage freeze.
The rally coincides with industrial action from PSA hospital clerical workers, and members of the SFWU who are employed by Idea Services and the hospital.
The PSA members are striking for three hours from 11.30am, the Idea Services SWFU workers from 11.30am to 8.30pm (covering parts of two shifts), and hospital SWFU workers from 11am to 3pm.
The hospital SFWU staff include orderlies, cleaning staff, security and those providing home help services.
Otago District Health Board diagnostic and support services group manager Sonja Dillon said contingency plans were in place for the stoppage, but eight people scheduled for home-help visits on Friday would be affected.
Board operations manager Megan Boivin said the PSA clerical workers' stoppage, although longer than the two held already, was not expected to cause difficulties.
Plans were in place, and because the rally would occur in the lunch hour, there was limited outpatient activity.
People were understanding about any delays, she said.
Idea Services Otago area manager Daniel Barnett said the organisation had contingency plans and it would be business as usual.
The organisation had received an overall funding increase of only 1.2% from the Government this year, which was insufficient to cover other cost increases.
IHC chief executive Ralph Jones said successive governments had failed to address the issue of the low wage rates of workers relative to similar sectors.
The wage restraint also applied to IHC managers.
New Zealand Educational Institute support staff, who have been offered no pay increase this year, are expected to join the rally.
The rally will be addressed by MPs Clare Curran and Pete Hodgson, Unions Otago convener Glenda Alexander and possibly some workers.
PSA organiser Julie Morton said it was hoped people outside the unions would join the protest to show their support.
