A consultation period has begun over plans by Birmingham City Council to shut five children's homes.
The GMB union said 170 jobs were under threat from the closures, which will save the council more than £3m.
The council said it wanted to reduce the number of children in residential care while increasing its rates of fostering and adoption.
It said homes identified for closure were based on performance and Ofsted inspection ratings.
The homes that will shut are Chamberlain Road in Billesley, Fountain Road in Harborne, Kings Lodge in Oscott and South Acre and Viscount House, which are both in Dudley.