A major attraction of multiple pulse NMR techniques is their ability to resolve complex spectra into more easily interpretable forms. For example, one-dimensional editing of 13C spectra by either polarization transfer (I) or spin-echo (2) methods is fmding increasing use to obtain separate 13C subspectra for CH, CH2, and CH3 moieties. Such spectra, for a variety of reasons, often display variable phase and intensity distortions over the spectral range of interest. In general we may divide such distortions into two types: (i) those which arise from rf pulse imperfections, because of either rf inhomogeneity, or flip-angle variations resulting from offsets from the carrier frequency, and (ii) those which arise from an incorrect setting (often a range of J values in a sample makes this unavoidable). Type (i) distortions are an inherent characteristic of an instrument and are more deleterious in spectrometers with long r/2 pulse times. For example, with an instrument operating at 250 MHz for proton NMR (63 MHz for “C) it is unrealistic to expect a transmitter which produces a tr,2 of 25 ~.lsec for 13C (10 kHz of pulse power) to yield a satisfactory (X pulse) inversion of the magnetization over the complete 13C spectral region ( 15 kHz). As a consequence., all pulse sequences which must by their nature include refocusing pulses produce spectra with phase and intensity distortions. A good example of type (ii) distortions occurs in the DEPT pulse sequence, written in simplified form below for polarization transfer from ‘H to 13C.