Union activists have lobbied hospital chiefs in Blackpool as part of their campaign over pay.
Members of Unison handed out leaflets to members of the Blackpool Teaching Hospitals NHS Foundation Trust when it held its meeting in public this week.
The union is campaigning on behalf of cleaners at Blackpool Victoria Hospital employed by private contractor Compass over what they claim is their employers’ failure to match NHS pay rates and working conditions.
Action has included a two-day strike, and now Unison wants the hospital board to put pressure on Compass to meet its demands.
Joanne Thompson, a domestic at BVH, was among those lobbying the meeting.
Speaking beforehand, she said: "The situation is unfair and causing a lot of friction in the hospital because domestics are working side by side on different pay rates.
"It means someone like me has to do extra overtime in order to earn a decent wage and be able to support my 12-year-old daughter."
Unison says most of the workers affected are paid only the minimum wage rate of £8.21 an hour, yet work alongside colleagues who are employed directly by the NHS, where the lowest rate is £9.03 an hour.
The difference of 82p an hour is worth £1,600 a year for full-time staff, the union says, adding that Compass staff are further disadvantaged by receiving no shift bonuses for working weekends and bank holidays.
In addition, they receive only statutory sick pay, whereas their NHS colleagues are able to access a comprehensive sick pay scheme.
Compass has said it is committed to resolving the issue.
A spokesman for Medirest, part of the Compass group, has previously stated its pay rates are set out in its client contracts and agreed in partnership with NHS Trust clients.