OBJECTIVE Molecular pathogenesis of Down syndrome (DS) is still incompletely understood. Epigenetic mechanisms, including miRNAs gene expression regulation, belong to potential influencing factors. The aims of this study were to compare miRNAs expressions in placentas with normal and trisomic karyotype and to associate differentially expressed miRNAs with concrete biological pathways. METHODS A total of 80 CVS samples - 41 with trisomy 21 and 39 with normal karyotype - were included in our study. Results obtained in the pilot study using real-time PCR technology and TaqMan Human miRNA Array Cards were subsequently validated on different samples using individual TaqMan miRNA Assays. RESULTS Seven miRNAs were verified as upregulated in DS placentas (miR-99a, miR-542-5p, miR-10b, miR-125b, miR-615, let-7c and miR-654); three of these miRNAs are located on chromosome 21 (miR-99a, miR-125b and let-7c). Many essential biological processes, transcriptional regulation or apoptosis, were identified as being potentially influenced by altered miRNA levels. Moreover, miRNAs overexpressed in DS placenta apparently regulate genes involved in placenta development (GJA1, CDH11, EGF, ERVW-1, ERVFRD-1, LEP or INHA). CONCLUSION These findings suggest the possible participation of miRNAs in Down syndrome impaired placentation and connected pregnancy pathologies. © 2016 John Wiley & Sons, Ltd.