The discovery of microRNAs (miRNAs) and their link with cancer has opened a new era in cancer therapeutics. Approximately, 18-24 nucleotides long, miRNAs can up-regulate or down-regulate gene expression in many cancer types and are respectively categorized as oncogenes (oncomirs) or tumor suppressors. Expression profiles of miRNAs with biomarker potential can be used for the classification, diagnosis, therapeutic treatment, and prognosis of different cancer types. miRNA mimics and miRNA antagonists are the two main approaches to miRNA-based cancer therapies that respectively inhibit oncomirs or restore the expression of tumor suppressive miRNAs. This review serves to provide some general insight into miRNA biogenesis, cancer related miRNAs, and miRNA therapeutics. Drug Dev Res 76 : 382-388, 2015. (c) 2015 Wiley Periodicals, Inc.