 The company pioneered breakfast fast food with the introduction of the Egg McMuffin in 1972 when market research indicated that a quick breakfast would be welcomed by consumers.Five years later McDonald's added a full breakfast line to the menu, and by 1987 a quarter of all breakfasts eaten out in the United States came from McDonald's restaurants.In test market locations, such as New York City, McDonald's added a full breakfast line to its menus in 1975.