The Amercian company – which has more outlets than McDonald's in the UK and is famous for its Italian Big, Meaty, Tasty, which at 6in-long contains 405 calories – could serve up meals at Parrs Wood High School in Didsbury.
It would be the first time Subway has opened a branch at a UK school.
Headteacher Andy Shakos said the discussions in the Subway concession were at an early stage – and insisted a broad range of food would still be available.
But critics, including TV chef Simon Rimmer – whose award-winning restaurant Greens is nearby – have raised concerns about the need for a tight control over the menu.
"A concession like this could serve sandwiches which have just 350 calories or sandwiches which are loaded up with fat and salt. It completely depends on how this concession operates.
There's nothing wrong with having a sandwich to eat every day but if it is an open menu, like it is on the high street, then it goes against everything we are trying to do in schools.
"Schools do need to remember the legal requirement to make sure they're meeting the national standards for school food."
A spokeswoman for Subway: "We typically don't discuss specific development until a store opens."
What do you think of this? Would you be happy with your child eating a Subway every day?