MicroRNAs (miRNAs) are a class of short, highly conserved, non-coding RNA molecules that regulate gene expression by specific binding to the messenger RNAs (mRNAs). At present, the researches on miRNAs have caused immense global concern, and expression of miR-139-5p plays a significant role in tumorigenesis, metastasis and recurrence, through regulating proliferation, migration, and invasion of cancer cells in lung cancer, esophageal cancer, breast cancer, tongue squamous cell carcinoma, hepatocellular carcinoma, etc. MiR-139-5p has a positive impact on the prognosis of cancer, and it can combine with some chemotherapeutic drugs to reverse resistance and enhance the sensitivity of radiotherapy. It also works in the cells and tissues of other diseases, including nerve cells, and inflammation. This article reviewed the progress of miR-139-5p.