Families and Communities Minister Jay Weatherill and Environment Minister Gail Gago are the biggest losers in Premier Mike Rann's surprise mid-term Cabinet reshuffle.

Two-thirds of government ministers have been shifted and new portfolios created in the shuffle, but there are no new faces.

Mr Weatherill loses Families and Communities, Housing, Ageing and Disability, keeps Aboriginal Affairs and takes on Environment and Conservation and the new portfolio of Early Childhood Development.

Ms Gago loses Environment and Conservation and Mental Health and Substance Abuse, taking on the less-desirable portfolios of Status of Women and Consumer Affairs.

Former Consumer Affairs Minister Jennifer Rankine is the big winner of the day, moving into the newly-created role of Minister for the Northern Suburbs and Mr Weatherill's old portfolios of Families and Communities, Housing, Ageing and Disability.

Michael Wright hands the poisoned chalice of Industrial Relations to Employment Minister Paul Caica, exchanging it for Police and Emergency Services.

Mr Rann said the reshuffle, announced in parliament this afternoon, was "not about creating winners and losers".

"The changes are designed to broaden the experience of ministers," he said.

"I think it is important to freshen up the ministry every few years to keep new ideas flowing and new perspectives on issues."

The ministers will be sworn in at Government House tomorrow morning.