In a pulsed nuclear magnetic resonance method of analysis, in which a single radiofrequency pulse is applied using an irradiation coil which provides an inhomogeneous radiofrequency field across the sample volume, the inhomogeneity of this field ensures that some sample regions experience a radiofrequency pulse which is closer to a .pi./2 pulse angle than for other regions, resulting in a larger signal intensity from the former regions as compared to the latter. If a second pulse is applied after the first, prior to acquisition of the signal, and if the phase of this pulse is alternated through the four phases: 0.degree., 90.degree., 180.degree. and 270.degree., during a series of transients, then, provided the receiver phase is changed by 180.degree. when the second pulse phase is changed by 90.degree., the signal intensity will accumulate from regions where the second pulse angle is .pi. radians and there will be discrimination against regions where the second pulse angle differs markedly from .pi. radians. This discrimination towards certain sample regions can be improved by adding further pulses after the second pulse provided the phase of each additional pulse is alternated through all four 90.degree. phase shifts, during a series of transients, independently of the phase alternation of the other pulses, and provided that for each individual 90.degree. phase shift, the receiver phase is changed by 180.degree.. In its simplest form, such a series of pulses may be represented by .theta.;(2.theta.[.+-.x,.+-.y]).sub.n indicating n phase alternated pulses additional to the first excitation pulse, where these additional pulses are twice as long as the first pulse.