The observation by 27Al magic angle spinning NMR of distinct Al tetrahedral sites in TPA-ZSM-5 (TPA = Pr4N+) in contrast to Na, H-ZSM-5 is related to the TPA/Al ratio in zeolite TPA-ZSM-5. For TPA-ZSM-5 with a TPA/Al ratio >1, only 1 27Al resonance is obsd. at 53.5 ppm. In the case of a TPA/Al ratio <1, an addnl. 27Al resonance is obsd. at 60.0 ppm, due to the hydrated Na ions needed for the neutralization of AlO4- tetrahedrons not charge compensated by TPA+.