Barnsley East MP Michael Dugher is urging the government not to close a children's heart surgery unit in Yorkshire.
The department treats children with heart conditions across the region, including many from Barnsley.
It is under threat of closure as part of plans to reduce the number of hospital's providing the service from 11 to six or seven.
Mr Dugher has written to the secretary of state for health Andrew Lansley calling on the government to retain the unit based at Leeds General Infirmary.
"The excellent unit in Leeds serves thousands of people in Barnsley and more than 5.5 million people across the region," he said.
"I am extremely concerned that if this unit closes, families in Barnsley will be forced to take their children to centres as far away as Newcastle, Liverpool or even London for lifesaving surgery. In emergency situations, this could put lives at risk."
The NHS has launched a four-month public consultation over the proposals.
"I would like to encourage people in Barnsley to contact me with their views and experiences of the unit so that I can pass them on and add them to the consultation submission," he said.
