1. Star Wars: Episode IV - A New Hope (1977)
2. Star Wars: Episode V - The Empire Strikes Back (1980)
3. Star Wars: Episode VI - Return of the Jedi (1983)
4. Star Wars: Episode I - Phantom Menace (1999)
5. Star Wars: Episode II - Attack of the Clones (2002)
6. Star Wars: Episode III - Revenge of the Sith (2005)
It's worth noting that this is the release order, not the chronological order of the story. The prequel trilogy (Episodes I-III) takes place before the original trilogy (Episodes IV-VI).