Ellen DeGeneres forgot she guest starred on Mad About You

Ellen DeGeneres forgot she once appeared in sitcom Mad About You while chatting with the show's cast on Tuesday.

The TV host was interviewing stars Helen Hunt and Paul Reiser, who played Paul and Jamie Buchman, for the latest instalment of The Ellen DeGeneres Show when producers aired a clip of the comedian's cameo appearance on the programme.

"I had to be reminded!" Ellen joked of her involvement with the popular U.S. sitcom. "But it's so funny, I don't remember it still even after looking at it."

However, Paul was on hand to support the 61-year-old, quipping: "As did we!"

Meanwhile, Helen insisted she didn't forget, saying, "I remember vaguely the feeling of like, 'This is a lot of talent... Why did we even think you'd say yes? And why did you say yes!?'"

Mad About You aired on NBC from 1992 to 1999, and will return for a 12-episode revival for Spectrum's On Demand platform.

Speaking about the reboot, the stars admitted having their real-life kids leave home paved the way for the latest series.

"Paul just went through empty nest. I'm about to go through it. So we thought there'd be 12 stories in there somehow," Helen explained.

The new series of Mad About You debuts on Wednesday.