The recent discovery of tiny microRNAs (miRNAs) has brought about awareness of a new class of regulators of diverse pathways in many physiological and pathological processes, such as tumorigenesis. They modulate gene expression by targeting plethora of mRNAs, mostly reducing the protein yield of a targeted mRNA. With accumulation of information on characteristics of miR-205, complex and in some cases converse roles of miR-205 in tumor initiation, progression and metastasis are emerging. miR-205 acts either as an oncogene via facilitating tumor initiation and proliferation, or in some cases as a tumor suppressor through inhibiting proliferation and invasion. The aim of this review is to discuss miR-205 roles in different types of cancers. Given the critical effects of deregulated miR-205 on processes involved in tumorigenesis, they hold potential as novel therapeutic targets and biomarkers.