Proton-proton collisions at the LHC are starting in the next few months, and with that the challenges of the ATLAS collaboration. B physics measurements will be ones of the first to come, so we are getting ready for early data. The ATLAS B Physics program is very rich and I will report on the expected measurements on B rare decays - such as Bs to mu+mu- -, on B lifetime measurements at the early data, and other measurements we expect to achieve once luminosity increase.