The change in chemical shift ( ∆δ) observed for a given nucleus, when shifting from an isotropic medium to a strongly oriented, liquid crystalline phase, contains valuable information on the orientation of its chemical shift anisotropy (CSA) tensor relative to the molecular alignment tensor. 1 Analogously, we have demonstrated 2 a dramatic improvement in the agreement between observed and predicted magnetic field dependence of 15N chemical shifts in a very weakly, magnetically aligned protein -DNA complex upon inclusion of dipolar coupling constraints in the structure calculation. 3 In that case, the minute changes in 15N shift and the very small one-bond 15N-1H and13CR-1HR dipolar couplings resulted from the field-dependent degree of molecular alignment, 3 induced by the magnetic susceptibility anisotropy of the complex. 4 Use of a dilute liquid crystalline medium consisting of phospholipid bicelles 1,5 makes it possible to obtain much higher degrees of molecular alignment while nevertheless retaining the spectral simplicity of the regular isotropic phase. 6 As we show here, it is straightforward to measure the difference in chemical shift frequency when switching from the liquid crystalline to the isotropic phase. The change is largest and most easily measured for backbone carbonyl atoms. The ∆δ13C′ values can either be used as constraints in the structure calculation or to evaluate the quality of the structure. This latter application is illustrated here, using the protein ubiquitin as a test case. The change in chemical shift for a given atom upon switching from the liquid crystalline to the isotropic phase is given by