Conrad's marriage to Playboy founder Hugh Hefner in July 1989 drew worldwide media attention. The comic strip Doonesbury referred to the event as the belated end of the 1970s. The Hefners had two sons together: Marston Glenn Hefner (who shares his birthday with his father: April 9, 1990) and Cooper Bradford Hefner (September 4, 1991). Conrad transformed the Playboy Mansion into a more conservative household for her children.
After nine years of marriage, Conrad and Hefner separated although remained nominally married. Hugh Hefner was quoted, "I would've been happy to divorce her when we separated, but she wanted to remain married for our boys." Conrad then moved into a house next door to the Playboy Mansion. After an 11-year separation, Hefner filed for divorce stating irreconcilable differences in September 2009 after his youngest child turned 18; the divorce was finalized in March 2010.