People working at Salisbury District Hospital will have to pay to use staff car parks, it has been announced.
Bosses say the charges, which would be up to £20 a month, will contribute to car park maintenance, save money and encourage people to walk, cycle and use public transport.
The trust's board made the decision following a six-week consultation with staff.
Unions said the decision would "add to staff's financial pain".
A trust spokesman said the fee would range from £12 to £20 a month for full-time staff, depending on their basic pay.
He added that part-time staff or occasional users could pay £1 a day instead of the monthly rate, and there would be free parking for staff providing a community service, volunteers and motor-bikes in dedicated shelters.
The board agreed to monitor the impact on staff, look at more flexibility when demand is high, and that there would be a review after 12 months.
Trust chief executive Matthew Kershaw said there would be a review after 12 months, but he acknowledged the introduction of staff car parking charges "would not be popular".
The trust would explore options to support staff walking, cycling and using public transport to get to work, including more bike racks and better shower and changing facilities, he said.
A spokesman from the joint staff side unions said: "Staff have already had a real terms pay cut in two of the last three years and the pay rise in April 2010 was just 2.25% compared to the rate of inflation of 5.3%.
"With parking charges on top this is a cut of over 4% in pay for most staff and our members are outraged as they face a tough time ahead with a reduction in their standard of living."
He said the charges were "more about the trust raising additional income from its staff to address their financial challenge" than any concerns about green issues and staff welfare.