MCM-22 is a new molecular sieve that contains unique structural features. Si-29 MAS NMR studies of a highly siliceous MCM-22 prepared by the hydrothermal treatment of a [B]MCM-22 are presented and discussed in light of the proposed framework topology. The structural information obtained from this NMR investigation is complementary to and consistent with the structure proposed from X-ray diffraction measurements. The major conclusions of this present work are that MCM-22 contains at least one buried T-site in its framework structure that is not accessible to a channel wall and that the NMR data favor the orthorhombic form of the proposed structure.