To test the hypothesis that telomerase reverse transcriptase (TERT) as an RNA‐dependent RNA polymerase could be involved in the amplification of microRNA (miRNA), we have determined the levels of immature and mature miRNA in cultured neonatal rat cardiomyocytes, during the silencing of TERT by siRNA. The silencing of the TERT gene led to the reduction of both telomerase activity and the TERT mRNA expression when compared with scrambled RNA. TERT gene silencing resulted in the decrement of three studied mature miRNAs levels: miRNA‐21, miRNA‐29a and miRNA‐208a when compared with scrambled RNA; but miRNA‐1, it was not changed significantly. At the same time, levels of immature miRNA‐1 and miRNA‐208a were not changed, although the levels of immature miRNA‐29a and pri‐miRNA‐1 were decreased. The data obtained allow us to permit that TERT is a genome‐independent source of mature miRNA, and the changes in telomerase activity can significantly influence the level of miRNA in cardiomyocytes. Copyright © 2014 John Wiley & Sons, Ltd.