Hydatidiform moles (HMs) are abnormal conceptions with unique genetic bases and excessive placenta. Overlapping ultrasonographical and histological manifestations of molar and non-molar gestations and HMs subtypes makes accurate diagnosis challenging. Currently, immunohistochemical analysis of p57 and molecular genotyping have greatly improved the diagnostic accuracy, but they still have limitations. The differential expression of molecular biomarkers may be valuable for distinguishing among the subtypes of HMs and their mimics. Thus, biomarkers may be the key to refining HMs diagnosis. In this review, we provide a critical overview of the recent literature about potential diagnostic biomarkers and their subclassifications.