[en] A novel methodology for stereospecific NMR assignments of methyl (CH₃) groups of Val and Leu residues in fractionally ¹³C-labeled proteins is presented. The approach is based on selective 'unlabeling' of specific amino acids in proteins while fractionally ¹³C-labeling the rest. A 2D [¹³C-¹H] HSQC spectrum recorded on such a sample is devoid of peaks belonging to the 'unlabeled' amino acid residues. Such spectral simplification aids in unambiguous stereospecific assignment of diastereotopic CH₃ groups in Val and Leu residues in large proteins. This methodology has been demonstrated on a 15 kDa calcium binding protein from Entamoeba histolytica (Eh-CaBP)