Day nine of the Olympics in Beijing, featuring swimmer Michael Phelps' gold-medal triumph, drew 31.1 million US viewers to NBC.
It was NBC's biggest audience for a Saturday night programme since an episode of a spinoff of The Golden Girls, titled Empty Nest in February 1990, according to Nielsen Media Research data cited by the network.
On Saturday, Phelps, 23, gained the 14th gold medal of his career and his eighth at the Beijing Games.
The victory marked the most gold medals ever claimed by one athlete at a single Olympics, surpassing the previous record of seven golds won by swimmer Mark Spitz in 1972.
NBC Universal is a unit of General Electric Co.
The network has averaged 30 million viewers in prime time - on par with the numbers tuning in for American Idol - since the games opened.
