The cast change follows the announcement that from Sept. 3 Kevin McNally takes over from Adrian Dunbar in the role of playboy philanderer Bernard.
Ellison and Oberman step into their respective roles of American air hostess Gloria and German air hostess Gretchen on Oct. 1.
Both actors are best known for their television soaps; Oberman on "EastEnders" and Ellison on "Brookside."
Oberman's stage credits include Edmond for the National Theatre, The Oak Tree and School Play for Soho Theatre, Loot and Saturday, Sunday and Monday both for Chichester Festival Theatre.
Oberman has also co-written an updated Jewish version of Chekhov's classic called 3 Sisters on Hope Street with Kindertransport writer Diane Samuels. The play receives its world premiere at Liverpool's Everyman in January 2008. Elllison's theatre credits include Roxie Hart in Chicago both in the West End and on tour.
The current cast of Boeing-Boeing also includes Rhea Perlman, who recently made her West End debut in the farce as Bernard's long suffering house maid Bertha.
The revival of Marc Camoletti's comedy is helmed by Lord of the Rings director Matthew Warchuss and opened at the West End's Comedy Theatre on Feb. 15 following previews from Feb. 3.
The madcap plot centers on Paris-based playboy Bernard who has three air hostess fiancées. When his school friend Robert (Neil Stuke) arrives, Bernard relishes the chance to show his friend his first class operation at work. But Bernard had not reckoned on a change of airline schedules.
Boeing-Boeing originally opened in London in the mid-'60s and held the world record for the longest running comedy in the West End, playing over 2,000 performances before transferring to Broadway.
In 1965 John Rich directed the film version starring Tony Curtis and Jerry Lewis.
The current cast of Boeing-Boeing also includes Elena Roger, who starred in the title role of the recent West End revival Evita, and Amy Nuttall; Doon Mackichan.
For more on Boeing-Boeing, which is s produced in the West End by Sonia Friedman Productions, Act Productions, Matthew Byam Shaw, Robert G Bartner and Bob Boyett, call (0)870 0606637.