The Egg McMuffin was introduced in 1971 as McDonald's first major breakfast menu item.
Herb Peterson, a McDonald's franchisee in Santa Barbara, California, created the sandwich. It used an English muffin, a round egg, Canadian bacon, and cheese, giving the chain a compact breakfast product that could be prepared and served in the same quick-service style as its existing food.
The Egg McMuffin helped McDonald's build a breakfast identity rather than relying only on its traditional lunch and dinner menu. Its success contributed to the later expansion of breakfast service across the chain and made the McMuffin name a durable part of McDonald's product branding.
The sandwich is sometimes confused with later breakfast products such as the Sausage McMuffin or McGriddles. Those are separate items; the original Egg McMuffin is the product associated with the beginning of McDonald's major breakfast push.