Molecular biomarkers are widely recognized as having tremendous utility in cancer early detection, prediction, and prevention. Huge efforts have been put into searching of various molecular biomarkers for these purposes, yet there are few molecular biomarkers that have been approved by the Food and Drug Administration for clinical use. Discovery of novel molecular biomarkers is still urgently needed to create biological insights into early events of carcinogenesis and to predict the aggressiveness of early cancer. Noncoding RNAs (ncRNAs) are relatively unexplored molecules identified only one decade ago. With research on the basic biology and mechanisms of ncRNAs, they have rapidly been linked to etiology of diseases, particularly cancer. In this chapter, we will summarize ncRNAs, particularly microRNAs (miRNAs), a type of ncRNAs, as a new frontier for the discovery of cancer biomarkers in preneoplastic lesions and their usefulness as markers for the risk assessment, early detection, and diagnosis of cancer.