MicroRNAs (miRNAs) are posttranscriptional gene regulatory molecules that show regulated expression within ovarian tissue. Most research investigating miRNAs in the ovary has relied exclusively on in vitro analyses. In this review, we highlight those few studies in which investigators have illustrated an in vivo effect of miRNAs on ovarian function. We also provide a synopsis of how these small noncoding RNAs can impact ovarian disease. miRNAs have great potential as novel diagnostic biomarkers for the detection of ovarian disease and in the assisted reproductive technologies (ART) for selection of healthy viable oocytes and embryos.