Axial peaks arise from magnetization which is not frequencylabeled in at least one indirect dimension of a multidimensional NMR1 experiment.2 Because they correspond to incomplete coherence transfers, axial peaks represent a considerable magnetization reservoir. Here we show that the previously introduced projection technique3,4 allows the derivation of useful information from axial coherences. In these experiments3-15 the evolution of chemical shifts in the projected dimension gives rise to cosine modulation of the transfer amplitude, which leads to peak doublets encoding n + 1 chemical shifts in an n-dimensional spectrum. Axial single-quantum coherences which are frequency-labeled in all indirect dimensions except the projected one can be observed as peaks located at the center of the doublets. Simultaneous acquisition of projected and central peaks facilitates the symmetrization of the spectrum6,9,16 and the unambiguous assignment of multiple peak doublets with degenerate chemical shifts in the other dimensions.6,15 NMR experiments delineating exclusively scalar connectivities are either “out-and-stay” experiments, in which excitation and detection is on different nuclei, or “out-and-back” schemes, in which the magnetization is detected on the same proton which was initially excited (Figure 1).17 Moreover, the one-bond scalar coupling topology of the spins correlated in different indirect dimensions of out-and-back experiments (S, K, and L in Figure 1) may be bifurcated or linear. For “bifurcated out-and-back” 3D HS experiments, where underlined letters denote nuclei observed in a common dimension4 and the enclosed spins represent the two branches, recording of central peaks can be achieved as recently described for 3D HNN .6 After magnetization transfer from H to S, JSK and JSL at the branching point (Figure 1a) evolve simultaneously, and the spin with the larger coupling to S is detected in quadrature. The product operator terms SxKzLz and SyKz give rise to doublets and central peaks, respectively, which have opposite sign (see Figure 4 in ref 6). In the corresponding 4D experiment, the term SyKz would give rise to noninformative axial peaks. Most triple-resonance pulse schemes designed for proteins17 represent linear “out-and-back” experiments. In 3D HSKL (Figure 1b), JSK and JKL evolve during sequential transfer steps. Hence, central peaks have to come from magnetization which has been transferred to K, but not to L. With HSQC-type magnetization transfer and K detected in quadrature, the doublets and central peaks arise from the product operator terms SzKzLy and SzKy, respectively with peak patterns as in 3D HS (see supporting information). The transfer amplitudes of doublets and central peaks are proportional to sin(πJKLτ) and cos(πJKLτ), respectively, where τ is the duration of the transfer delay. Considering JKL only, all three peaks have the same intensity if cos(πJKLτ°) ) 0.5 sin(πJKLτ°) at τ° ) 0.61/ (2JKL). τ° is close to the transfer maximum when rapid T2relaxation and/or additional passive couplings prevent a complete transfer. Then, the central peaks are exclusively derived from otherwise discarded magnetization and are acquired without extra expense of instrument time.