The present invention discloses a set of human microRNAs, or a primary transcript for such microRNAs, or a precursor of such microRNAs, or a mimic of such microRNAs or a combination thereof, and their use as medicaments for inducing proliferation of cardiomyocytes for the prevention and treatment of heart diseases associated with a loss of cardiomyocytes. The invention also relates to a method for screening microRNAs and biological and therapeutically active compounds for their ability to increase proliferation of cardiomyocytes.