High-throughput sequencing made deep analysis of immune receptors repertoires possible. However, B cells' ability to accumulate hypermutations indistinguishable from PCR errors along whole variable domain and low quality of extended sequencing still impose a serious obstacle to analysis of full-length variable immunoglobulin sequence repertoires. In present review we demonstrate how molecular barcoding technique (unique molecular identifers, UMI) and bioinformatics analysis provide nearly error-free immunoglobulin repertoires profling of complex B-cell populations comprising minor hypermutated subvariants.