Sierra Mist is a lemon-lime flavored soft drink, The new formula, branded as Sierra Mist, was introduced by PepsiCo in 1999, replacing Slice and Storm, and eventually became available in all United States markets by 2003. PepsiCo owns the rights to the similar 7 Up and Coca-Cola's Sprite brand outside the U.S. and therefore has not yet introduced Sierra Mist in international markets.

Following initial test marketing, PepsiCo first introduced Sierra Mist in 1999, replacing similar soft drinks such as lemon-lime Slice and the test-marketed Storm. The selection of the name "Sierra Mist" was based on favorable market research involving 2,000 people. "Sierra Mist" was selected from over 1,000 possible names. It is worth noting that "Sierra" had previously been a proposed name for what became the original (10% juice-formula, lemon-lime) Slice in 1984.Diet Sierra Mist was also introduced in 2000, and sales of both diet and original Sierra Mist totaled $100 million in its first year of production.