The article reviews the role of microRNAs (miRNAs) in cancer. MiRNAs are small non-coding RNAs that play a crucial role in gene expression regulation by post-transcriptionally inhibiting target mRNAs. The discovery of miRNAs has provided new insights into the regulation of gene expression, particularly in post-transcriptional processes. MiRNAs are involved in various cellular processes, including proliferation, apoptosis, invasion, and angiogenesis. In cancer, miRNAs are often aberrantly expressed, with many being up-regulated or down-regulated compared to normal tissues. These changes in miRNA expression can contribute to cancer development and progression. The article discusses specific miRNAs that have been implicated in cancer, such as miR-17-92 cluster, miR-21, miR-155, let-7, and miR-34s, and their roles in different aspects of cancer biology. MiRNAs can act as oncogenes or tumor suppressors, and their dysregulation can lead to uncontrolled cell growth and metastasis. The article also highlights the potential of miRNAs as diagnostic and therapeutic tools in cancer, emphasizing the need for further research to optimize their clinical applications.The article reviews the role of microRNAs (miRNAs) in cancer. MiRNAs are small non-coding RNAs that play a crucial role in gene expression regulation by post-transcriptionally inhibiting target mRNAs. The discovery of miRNAs has provided new insights into the regulation of gene expression, particularly in post-transcriptional processes. MiRNAs are involved in various cellular processes, including proliferation, apoptosis, invasion, and angiogenesis. In cancer, miRNAs are often aberrantly expressed, with many being up-regulated or down-regulated compared to normal tissues. These changes in miRNA expression can contribute to cancer development and progression. The article discusses specific miRNAs that have been implicated in cancer, such as miR-17-92 cluster, miR-21, miR-155, let-7, and miR-34s, and their roles in different aspects of cancer biology. MiRNAs can act as oncogenes or tumor suppressors, and their dysregulation can lead to uncontrolled cell growth and metastasis. The article also highlights the potential of miRNAs as diagnostic and therapeutic tools in cancer, emphasizing the need for further research to optimize their clinical applications.