David Smith, of West Hill, Bridliington, was told his mobility scooter did not count as a vehicle and so could not use the fast food restaurant’s Drive Thru.
Mr Smith, 66, said: “They told me it’s not a vehicle.
“It’s got lights, indicators, it’s fully taxed and insured!”
Mr Smith, who served 23 years with the Royal Navy, has been using the mobility scooter since having an operation on his knee and being told he can not drive a car for six months.
He usually visits the Bridlington branch of McDonald’s, on Bessingby Way, a couple of times a week, and was keen to get back once the Drive Thru reopened.
He arrived early on its re-opening day last Tuesday so that he was first in line.
A fellow customer saw Mr Smith being turned away and offered to buy his food as part of his order.
But when he got home, Mr Smith was angered to find on the McDonald's website that - as he had thought - road-worthy mobility scooters are permitted to use McDonald’s Drive Thrus.
He returned to the restaurant but was turned away again by a security guard who also turned him away once more when he tried to use the Drive Thru the next day.
“It’s discrimination at its very worst,” said Mr Smith.
A spokesperson for McDonald’s said: “We apologise to this customer for the delay caused in using our Drive Thru.
“For everyone’s safety, our restaurant team were checking that mobility scooters were permitted in the Drive Thru lane and, due to its road-going nature, in this case it was.
“Unfortunately, during this short delay the customer left, however we hope to welcome him back in the near future.”