The Curse of the Bambino was a superstitious sports curse in Major League Baseball (MLB) derived from the 86-year championship drought of the Boston Red Sox between and . The superstition was named after Babe Ruth, colloquially known as "The Bambino", who played for the Red Sox until he was sold to the New York Yankees in 1920. While some fans took the curse seriously, most used the expression in a tongue-in-cheek manner.
Prior to the drought, the Red Sox had been one of the most successful professional baseball franchises. They won five of the first fifteen World Series titles, including the first in 1903, more than any other MLB team at the time. During this period, Ruth was a contributor to the Red Sox's three championships in , , and . Following the sale of Ruth, however, the once lackluster Yankees became one of the most dominant professional sports franchises in North America, winning more than twice as many World Series titles as any other MLB team. The curse became a focal point of the Yankees–Red Sox rivalry over the years.
Talk of the curse as an ongoing phenomenon ended when the Red Sox won the 2004 World Series. The Red Sox's championship was prefaced by them overcoming a 3-0 deficit against the Yankees in the 2004 American League Championship Series (ALCS), the first and, as of 2022, only time an MLB team won a best-of-seven playoff series after losing the first three games.
The curse had been such a part of Boston culture that when a "reverse curve" road sign on Longfellow Bridge over the city's Storrow Drive was graffitied to read "Reverse The Curse," officials left it in place until the Red Sox won the 2004 World Series. After the World Series that year, the road sign was edited to read "Reversed Curse" in celebration.
Although it had long been noted that the selling of Ruth had been the beginning of a decline in the Red Sox' fortunes, the term "curse of the Bambino" was not in common use until the publication of the book The Curse of the Bambino by Dan Shaughnessy in 1990.