MicroRNA-24 (miR-24) has been widely studied in a variety of human cancers, which plays different roles in specific type of cancers. In the present review, we summarized the recent surveys regarding the role of miR-24 in different human cancers. On the one hand, miR-24 was reported to be down-regulated in some types of cancer, indicating its role as a tumor suppressor. On the other hand, it has shown that miR-24 was up-regulated in some other types of cancer, even in the same type of cancer, suggesting the role of miR-24 being as an oncogene. Firstly, miR-24 was dysregualted in human cancers, which is related to the clinical performance of cancer patients. Thus miR-24 could be used as a potential non-invasive diagnostic marker in human cancers. Secondly, miR-24 was associated with the tumor initiation and progression, being as a promoter or inhibitor. Therefore, miR-24 might be an effective prognostic biomarker in different type of cancers. Lastly, the abnormal expression of miR-24 was involved in the chemo- and radio- therapies of cancer patients, indicating the role of miR-24 being as a predictive biomarker to cancer treatment. Totally, miR-24 contributes to tumorigenesis, tumor progression, and tumor therapy, which closely related to clinic. The present review shows that miR-24 plays a double role in human cancers and provides plenty of evidences to apply miR-24 as a potential novel therapeutic target in treating human cancers.