What a Difference a Day Makes (Grey's Anatomy)

"What a Difference a Day Makes"
Grey's Anatomy episode
An episodic screenshot displaying Stevens listening to Karev saying his wedding vows.
Episode no.	Season 5 Episode 22
Directed by	Rob Corn
Written by	Shonda Rhimes
Featured music	"First In Line" "Another Likely Story" "Turn To Stone"
Original air date	May 7, 2009 (2009-05-07)
Guest appearance
Jeffrey Dean Morgan as Denny Duquette
Episode chronology
← Previous "No Good at Saying Sorry (One More Chance)" Next → "Here's to Future Days"
Grey's Anatomy season 5
List of episodes

"What a Difference a Day Makes" is the twenty-second episode of the fifth season of the American television medical drama, Grey's Anatomy and the show's 100th episode overall. It is written by series creator Shonda Rhimes and directed by Rob Corn, the episode was originally broadcast on the American Broadcasting Company (ABC) in the United States on May 7, 2009.

Grey's Anatomy centers around a group of young doctors in training. In this episode, a wedding takes place. The episode received widespread critical acclaim, with Heigl and Chambers' performances receiving high praise. The initial airing was viewed by 15.326 million people and garnered a 5.3/14 Nielsen rating/share in the 18–49 demographic.