“Xanadu” will roller skate off into the sunset next month, with the Broadway tuner setting a closing date of Oct. 12.

Well reviewed but never a big box office draw, the musical is the first casualty to be announced during the Street’s traditional September downturn.

Last week, in a frame when sales for most shows picked up a bit, the weekly tally for “Xanadu” fell by nearly $95,000 to $166,695. Drop was largely attributable to the departure of Whoopi Goldberg, who finished her limited engagement with the musical on Sept. 7.

Tuner, which has not yet recouped its capitalization costs of between $4 million and $5 million, has so far grossed $16.8 million since it began Rialto perfs in May 2007 ahead of its July 10, 2007, opening.

Weekly sales rarely topped the $300,000 mark after its first summer on the boards, with the show’s highest tally, about $460,000, coming during the November 2007 stagehands strike that darkened most other shows on the Rialto.

Property will continue to generate revenue in future productions, including one planned for November at the La Jolla Playhouse (whose a.d., Christopher Ashley, helmed “Xanadu”) and then a six-month stint at Chicago’s Drury Lane, to be followed by a national tour. A Korean production opened recently, and a London staging (co-produced by David Ian and John Gore) is in the works, as are incarnations in China, Australia and the Philippines.

A spoof of the notorious 1980 roller disco flop that starred Olivia Newton-John, “Xanadu” overcame dismissive pre-opening buzz to garner strong press, a group of ardent fans and four Tony noms. In the spring the show picked up an Outer Critics award for tuner and a Drama Desk for book writer Douglas Carter Beane (“The Little Dog Laughed”).

Score is comprised of tunes from the pic by Jeff Lynne and John Farrar.

Cast is toplined by Kerry Butler and Cheyenne Jackson, who stepped in during the preview period when original cast member James Carpinello was forced to withdraw due to a skate-related injury. Ensemble also features Jackie Hoffman, Mary Testa and Tony Roberts.

Rob Ahrens leads a producing team made up mostly of Broadway tyros, including Tara Smith, B. Swibel, Dan Vickery, Cari Smulyan, Dale Smith and Sara Murchison.

By the time it closes at the Helen Hayes Theater, “Xanadu” will have played 528 perfs plus 49 previews. The Hayes is set to be purchased by Off Broadway’s Second Stage, although the org won’t begin programming in the venue until 2010.