A system and method of generating Radio Frequency (RF) pulses RF(t) in a Multi-band (MB) Magnetic Resonance Imaging (MRI) system is presented. The method includes determining a dirac comb function, the period of the comb function determining the frequency separation of the excitation bands. The method further includes determining a single band frequency selective pulse, defining the envelope of a pulse of RF(t), and the shape of individual excitation frequency bands in the frequency domain. The method further includes determining the shape of RF(t) during each period, and is used to modulate uniformity and/or number of individual excitation bands in the frequency domain. RF(t) pulses are generated in the MRI system simultaneously with an MRI gradient so as to simultaneously excite multiple slices within a subject, wherein the RF(t) pulse create a spin response.