Rotherham and Stocksbridge steel jobs are being cut.
Liberty Steel is cutting 355 jobs in the UK - because of falling demand.
280 will go at its plant in Stocksbridge while around 70 are being axed at Newport in South Wales.
The company says it has had to review its British business because the steel industry in the UK is facing "challenging conditions".
Rotherham MP Sarah Champion has raised concerns over job losses, and says she'll be challenging the company - and the government - 'to secure the long term future of this key industry'.