The 2008 Iowa Republican presidential caucuses took place on January 3, 2008. The Iowa Republican caucuses are an unofficial primary, with the delegates to the state convention selected proportionally via a straw poll. The Iowa caucuses mark the traditional formal start of the delegate selection process for the 2008 United States presidential election.

The Iowa caucuses are quadrennial electoral events for the Democratic and Republican parties in the U.S. state of Iowa. Unlike primary elections, where registered voters cast ballots at polling places on election day, Iowa caucuses are meetings where voters gather to discuss and select candidates for their registered party. Political parties hold the caucuses, in contrast to most state-run primaries. Both presidential and midterm elections in Iowa use caucuses. The caucuses are also held to select delegates to county conventions and party committees, among other party activities.