MicroRNAs are short noncoding 18-25 nucleotide long RNA which bind and inhibit mRNA. Currently, there are over 1000 known human microRNAs, and microRNAs control over 50% of mammalian protein coding genes. MicroRNAs can be overexpressed or repressed in different diseases and inhibition or replacement of microRNAs is a promising area of study for therapeutics. Here we review the current knowledge of microRNA therapy, and discuss ways in which they can be utilized. We also discuss different methods of delivery of miRNA, and current clinical trials of microRNA-based therapies for disease. Finally we discuss the current limitations in the field, and how these limitations are being overcome.