The dependence of the core level binding energies, E-b, of Si, Al, and O bonded in zeolites on the concentration of skeletal Al is investigated. The line shape changes of Al KLL Auger spectra appearing with decreasing concentration of Al in zeolites are described. Initial and final state effects influencing core level binding energies of zeolites are discussed on a qualitative level. Different screening of the hole states localized on Al and Si is demonstrated. Evidence is shown for the dominant influence of initial state effects on the core level E-b values of Si and Al.