Neuwirth, as Velma, will play off Belle Calaway's Roxie and Robert Urich's Billy Flynn in the "musical vaudeville" (the 1975 tuner's original billing) about getting away with murder in Jazz Age Chicago.
Duncan joined the cast in summer 1999, giving her image and the show itself a jolt of attention. She broke her foot in rehearsals and her debut in the show was delayed, but she recovered well enough to earn raves for performing John Kander and Fred Ebb's pastiche songs and dancing the moves of original director-choreographer Bob Fosse.
Duncan, 53, is known for playing squeaky-clean roles in Peter Pan, My One and Only and The Boy Friend, and for pushing Wheat Thins crackers in popular commercials. In Chicago, she plays a promiscuous, lying murderess who goes into vaudeville.
Urich, who appeared as Billy Flynn in Chicago on national tour in Detroit and Washington DC, brought his tuxedo to Broadway on Jan. 5 and continues to Feb. 13. Urich is best known for his TV roles on "Vegas," "Spenser: For Hire" and "The Love Boat: The Next Wave."
Neuwirth won the Tony Award for playing Velma in the hit revival. Brent Barrett returns to the company as Billy Feb. 15.
Tony-nominated Marcia Lewis remains as Matron Mama Morton.
The 1975 John Kander-Fred Ebb-Bob Fosse musical became a smash hit in revival (1996 and still going), eclipsing the original respectable run (923 performances).
The 1996 revival first starred Neuwirth as Velma and Ann Reinking as Roxie, playing roles originated by Chita Rivera and Gwen Verdon, respectively. Walter Bobbie directed, Reinking choreographed "in the style" of Fosse.
For information about Chicago, call (212) 239-6200.