MicroRNA molecules (miRNAs) are naturally occurring triggers of the RNA-interference pathway. The first identified miRNA, lin-4, was discovered in Caenorhabditis elegans >20 years ago. What began as a curiosity in this model organism has expanded into almost every area of biology; there are now 326 confirmed miRNA genes in humans and the total is predicted to reach 1000. Each miRNA has the potential to regulate hundreds of mRNAs; therefore, there are likely to be few biological pathways not impacted by miRNA regulation. Recent evidence has suggested that miRNAs might be viable therapeutic targets for a wide range of diseases, including cancer. A recent article by Stoffel and colleagues has demonstrated remarkably effective inhibition of miRNAs in vivo, thus providing an entry point into the promising new arena of miRNA therapeutics.