MicroRNAs (MiRNAs) are small non-coding RNAs that regulate their target genes expression at the post-transcriptional level. As accumulating properties of miR-205 have been identified, complex roles of miR-205 in tumor initiation and progression are emerging. MiR-205 acts either as a tumor suppressor through inhibiting proliferation and invasion, or as an oncogene through facilitating tumor initiation and proliferation, depending on the specific tumor context and target genes. In this review, we focus on the properties of miR-205 in cancers to shed light on better management of various fatal malignancies. Moreover, we discuss epigenetics that may account for the fluctuation of miR-205 expression. In addition, we sketch a network of miR-205 and its targets to further elucidate the mechanisms through which miR-205 exerts its multiple functions.