It is not known precisely what the surgery entails. Philharmonic spokesman Eric Latzy told the web site Musical America that "it involves a toe." Maazel is expected to make a full recovery.
The conductor had emergency cataract surgery last year, which caused him to miss a production of Carmen at the Seville International Film Festival.
Maazel was scheduled to conduct six concerts. The August 18, 19, and 20 concerts would have included two of his own works—Monaco Fanfares and Farwells—and Richard Strauss's An Alpine Symphony.
Those concerts will now be conducted by the Tugan Sokhiev, recently named principal guest conductor of the Orchestre du Capitole de Toulouse, and the program will feature Borodin's In the Steppes of Central Asia, the 1919 version of Stravinksy's Firebird, and Rimsky-Korsakov's Scheherazade.
Yannick Nezet-Seguin, artistic director of the Orchestre Metropolitain in Montreal, will take over Maazel's August 24, 26, and 27 concerts, and the program will remain unchanged, with Mozart's Piano Concerto in C minor and Bruckner's Symphony No. 8. Stephen Kovacevich will be the concerto's soloist.
A spokeswoman for the Sydney Symphony said of Maazel's sudden cancellation, "Obviously we're disappointed. . . but we look forward to having him back in the future." Ticket holders for the concerts are being notified of the change in plans.