A hotel official said Friday that the brother-sister duo, who starred in the ''Donny & Marie'' variety show in 1976, will play Tuesday-Saturday shows for 26 weeks spread over eight months at the Flamingo Showroom.

The 90-minute show, beginning Sept. 9, will be presented by Danny Gans and Chip Lightman of GansLight Entertainment. It is being billed as a greatest-hits multimedia spectacle on a custom stage with multiple video screens and a cast of dancers.

''My version of a variety show has been what Vegas has known thus far,'' said Gans, an impressionist and comedian who has long played in Las Vegas. ''What we have now is a true variety show which conveys the real essence of America and the country's love of homegrown talent.''

Tickets, $85, $99 and $115, go on sale Monday for the engagement, which marks a return to Las Vegas for Donny and Marie. Their musical family, The Osmonds, shared the marquee at the former International hotel with Elvis Presley in the 1970s. The International is now the Las Vegas Hilton.

''Donny and Marie are timeless entertainers and cultural icons,'' said Don Marrandino, president of Flamingo Las Vegas. Financial terms of the deal were not disclosed.

The duo recently hosted the Miss USA pageant in Las Vegas, and are due to host ''America's Favorite Mom,'' on NBC next month. The Flamingo Showroom has been dark most of this month after entertainer Toni Braxton was hospitalized April 7 with chest pain.