The celebration goes back to the 1930s and falls on the first friday of June every year.
Doughnut retailers nationwide are offering free goodies.
At Dunkin Donuts, the doughnuts are free with the purchase of a beverage. The day also coincides with Dunkin Donuts' launch of the new glazed-donut breakfast sandwich.
Tim Horton's will do the same with a printout of a Facebook coupon.
For more information, visit Donut Day USA here.