Evidences have demonstrated key mediatory roles of microRNA-205 (miR-205) in normal physiology and its aberrant expression in many cancers. Indeed, miR-205 has been identified as both a tumour suppressive and oncogenic miRNA playing crucial roles in tumourigenesis through regulating different cellular pathways such as cell survival, apoptosis, angiogenesis and metastasis. As a tumour suppressor, miR-205 acts as an inhibitor of cell proliferation, migration and invasion. On the other hand, as an oncogene, miR-205 promotes tumour initiation and development. All these functions act through different target genes in various types of cancers. Also, miR-205 displays potential as a therapeutic target for different cancers. To conclude, miR-205 has important clinical and pathological correlations in different cancers and may act as a diagnostic and prognostic marker as well as new molecular target for cancer therapy.