Yes they will. Canon DSLRs accept any lens for the EOS system, which are labeled "EF". The Rebel, Rebel XT, Rebel XTI, 20D, and 30D also accept a new type of lens called an EF-S lens. You wouldn't be able to use an EF-S lens on any other Canon camera, digital or film. Your best bet is to stick with EF lenses if you plan to upgrade to a full frame DSLR, or continue to use a 35mm SLR.