Aim: To identify the shortest components of A13-A19, B12-B17 fragments capable for fibrillation and to validate the dependability of aggregation on the presence of hydroxyl group engaged in the ‘tyrosine kissing’. Materials & methods: Fragments A13-A19 and B12-B17 of insulin and all shortened analogues were obtained by using DMT/NMM/TosO^- as a coupling reagent. The aggregation was studied by three independent tests. Results: Studies on the susceptibility to aggregation of truncated analogs of insulin amyloidogenic core show three groups of peptides. Conclusion: Truncation of A13-A419 fragment shows that fibrous structures are formed by all peptides bearing ¹³H-LeuTyr-OH¹⁴. Propensity to aggregation was found for ¹⁶H-TyrLeu-OH¹⁷ B12-B17 fragment. Tyrosine residue modification by incorporation of tert-butyl group on hydroxyl function gave analogues still predisposed to aggregation.