Lemper is suffering from laryngitis and hasn't been in a Chicago performance at the Shubert Theatre since the matinee of Jan. 9. Standby Nancy Hess has played the vampy murderess Kelly, who sings "All That Jazz," Jan. 9-13.
A spokesman for the show said Neuwirth, the 1996 revival's original Velma, is back "as a favor to the producers and (songwriters) Kander and Ebb." Karen Ziemba remains in the cast as Roxie Hart.
Lemper, the sultry German star who played the London production of the lauded Chicago revival, is expected back Jan. 26.
Neuwirth is a recent refugee from another John Kander-Fred Ebb show. She departed the Arlington, VA, Signature Theatre production of their new musical, Over & Over, in late December 1998. "Artistic differences" between her and director Eric D. Schaeffer were cited.
Neuwirth was a Tony Award-winning dancer and actress (the 1986 revival of Sweet Charity) before she became a household name as Lilith on TV's "Cheers" and "Frasier."
For tickets and information on Chicago at the Shubert Theatre call (212) 239-6200.