This report represents initial studies of collagen mimetics with achiral peptoid-based trimeric sequences. The incorporation of achiral units into collagen-like structures is of considerable interest for the structural simplification of collagen-like biomaterials. The achiral unit Gly-Nleu-Nleu (where Nleu represents N-isobutylglycine) was positioned between Gly-Pro-Hyp trimeric repeats in collagen-like structures in order to examine the effect of an achiral block on triple helicity. A series of single chain structures, Ac-(Gly-Pro-Hyp)(n)-(Gly-Nleu-Nleu)(n)-(Gly-Pro-Kyp)(n)-NH2 (where n = 1-3), and a template-assembled structure, KTA-[Gly-(Gly-Pro-Hyp)(2)-(Gly-Nleu-Nleu)(2)-(Gly-Pro-Hyp)(2)-NH2](3) (where KTA represents cis,cis-1,3,5-trimethylcyclohexane-1,3,5-tricarboxylic acid), were investigated. Biophysical studies were carried out in both H2O and ethylene glycol (EG)/H2O (2:1, v/v) solvents, using circular dichroism and optical rotation measurements. Highly cooperative melting curves from optical rotation determinations were obtained for Ac-(Gly-Pro-Hyp)(n)-(Gly-Nleu-Nieu)(n)- (Gly-Pro-Hyp)(n)-NH2 (n = 2, 3) and KTA-[Gly-(Gly-Pro-Hyp)(2)-(Gly-Nleu-Nleu)(2)-(Gly-Pro-Hyp)(2)-NH2](3), revealing that the achiral trimer can participate in triple helical structures. These results were also supported by circular dichroism spectroscopy. For the molecules Ac-(Gly-Pro-Hyp)(3)-(Gly-Nleu-Nleu)(3)(Gly-Pro-Hyp)(3)-NH2 and KTA-[Gly-(Gly-Pro-Hyp)(2)-(Gly-Nleu-Nleu)(2)-NH2](3), the presence of collagen-like structures was also supported by H-1 NMR spectroscopy in H2O. For each structure, a distinct set of resonances, obtained at low temperature, disappeared once a thermal denaturation temperature was reached. Furthermore, the analysis of NOE cross-peaks established the close packing of Pro, Hyp, and Nleu. The spatial proximity of Pro and Nleu residues and of Hyp and Nleu residues belonging to different chains was confirmed by molecular modeling of triple helical AC-(Gly-Pro-Hyp)(3)-(Gly-Nleu-Nleu)(3)-(Gly-Pro-Hyp)(3)-NH2 .