Four y-glutamyl peptides were isolated from a hydrophilic extract of garlic bulbs. y-L-Glutamyl-S-(trans-1-propenyl)-L-cysteine has been isolated as a new genuine constituent of Allium sativum. For the first time detailed NMR data for y-L-glutamyl-S-allyl-L-cysteine, y-L-glutamyl-S-(trans-1-propenyl)-L-cysteine and y-L-glutamyl-S-allylthio-L-cysteine are reported. The structures of the four compounds were established on the basis of their spectral data (IR, FABMS, ¹H and ¹³C NMR). Extensive 2D heteronuclear correlated NMR experiments allowed the assignment of all proton and carbon resonances for all reported compounds.