Around 40 staff employed by private contractor Compass at Blackpool Victoria Hospital walked out this morning in protest of the company's failure to match health service pay rates and working conditions.
Their union, UNISON, announced plans for six days of strike action earlier this month.
They said that affected workers - around 300 in all - at both the Vic and St Helens Hospital 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 around £1,500 a year for full-time staff, the union claims.
Regional organiser Pat Woolham said: "Hospital staff have asked their employer for one thing - fairness. Compass workers can’t reasonably be expected to give their all while working alongside colleagues who are being paid more than them."
Compass has said its pay rates are set out in contracts with clients and discussions with employees, unions and NHS trusts began in May to reach a 'fair settlement'.