Colorectal cancer (CRC), the third most common cancer in the world, has no specific biomarkers that facilitate its diagnosis and subsequent treatment. MicroRNAs, small single-stranded RNAs that repress mRNA translation and trigger mRNA degradation, show aberrant levels in CRC by which these molecules have been related with the initiation, progression and drug-resistance of this cancer type. Numerous studies have shown that miRNAs influence cellular mechanisms related to cell cycle, differentiation, apoptosis and migration of cancer cells through post-transcriptionally regulate gene expression. Specific patterns of upregulated and down-regulated miRNA have been associated to CRC diagnosis, prognosis and therapeutic response. Concretely, down-regulated microRNAs represent attractive candidates, not only for CRC diagnosis, but for targeted therapies via tumor suppressor micro RNA replacement. This review shows a general overview of the potential uses of miRNAs in CRC diagnosis, prognosis, treatment with a special focus on down-regulated ones.