It follows a 6.4% rise in 2007/8 and a government announcement that senior public sector workers would have their pay frozen in 2010/11.
The most recent survey found that the median salary for a chief executive of a NHS foundation trust was £157,500 in 2008/9, compared with £147,500 for a chief executive of a non-foundation NHS trust.
Foundation trusts have more independence over the level of remuneration awarded to staff compared with other trusts including PCTs.
Mike Jackson, Unison senior national officer, said: ‘It is right that senior managers in the NHS get paid a decent wage. Running a hospital is a tough and very responsible job, and without competitive pay rates, hospitals will not be able to attract the right calibre of staff.
‘But it is not right for senior staff to get above inflation pay hikes, while the rest of the workforce get a below inflation pay deal.'