Winfrey and Letterman shared different sides to the story of the very public feud (now over) that supposedly started with the latter's scathing Academy Awards monologue.
Letterman also opened up about his 2009 sex scandal, in which he admitted to having affairs with "Late Show" staffers.
"Did you have to sleep on the couch?" Oprah asked.
"I slept a wide variety of places," Letterman replied.
In another show segment, the 65-year-old comedian and talk show host spoke about having to make people laugh every night while battling depression, telling Oprah that the mental illness is about more than feeling blue.
"It's like you get on an elevator and the bottom drops out," he said.
Members of Congress to keep receiving porn magazine
Justin Bieber crashes Drake Bell's album release party