A new method for the localization of NMR spectra in vivo is presented. Herein a series of selective 90 degrees pulses with different carrier frequencies in the presence of magnetic field gradients is saturating spins of unwanted regions. Only spins in the region of interest are left unaffected. The LOCUS (localization of unaffected spins) spectrum of this region is measured by a single 90 degrees excitation pulse. The FLASH imaging sequence combined with the LOCUS technique allows the identification of the region of interest.