New research shows that washing clothes at a minimum of 60C kills the deadly bacteria.
But there is a snag – most modern clothes are now cleaned only on a 40C cycle, meaning that the bug survives.
This is because delicate fabrics or bright colours can be ruined by washing them in water that is too hot.
And environmental campaigners insist that cooler temperatures should be used to save energy.
But hospital bosses are still urging people to think about their clothes before coming in.
They are under the spotlight for their failure to control the spread of MRSA.
But the bug exists in an estimated 30 per cent of the population and is often unknowingly carried into hospitals by patients or visitors.
Graeme Zaki, medical director for Portsmouth Hospitals NHS Trust, said: 'The MRSA bug is killed if you wash your clothes at 60C, but most are washed at 40C.
'It would be helpful for people to know that, and it is worth reminding people that MRSA exists in the community and many people bring it into hospital.'