The "Shrek" themed glasses were recalled last week because they're tainted with the toxic medal, cadmium.
Starting Wednesday, customers can return the glasses and fill out a refund slip.
McDonald's says it will refund $3 for every glass. Customers paid a $1.99 for them with a food purchase or $2.49 without a food purchase.
Seven million of the Shrek glasses were sold. Cadmium can cause kidney, lung and bone damage, especially in children.
