McDonald's first breakfast sandwich, introduced in 1972 by franchisee Herb Peterson, was the Egg McMuffin.
Peterson developed the sandwich in Santa Barbara, California, using an English muffin, a round egg, Canadian bacon, and cheese. The format gave McDonald's a compact breakfast item that could be prepared consistently and eaten conveniently.
The Egg McMuffin helped establish breakfast as a major part of McDonald's identity. Before its introduction, McDonald's was primarily associated with hamburgers, fries, and lunch or dinner service. The sandwich created a new daypart for the chain and later supported a much broader breakfast menu.
The Egg McMuffin is sometimes confused with the Sausage McMuffin, which uses sausage instead of Canadian bacon, or the later McGriddle. Its name also helped popularize the “Mc” naming pattern for McDonald's menu products. The sandwich remains one of the clearest examples of menu innovation becoming brand identity.