Over the past decade, research has shown that aberrant expression of micro RNA(mi RNA) is involved in colorectal cancer development and progression. Micro RNAs are small sequences of non-coding RNA that regulate expression of genes involved in important cellular functions, such as cell differentiation, multiplication, and apoptosis. A specific mi RNA may display the effects of a tumor suppressor or oncogene. Altered mi RNA expression is found in colorectal cancer(CRC) and patterns of mi RNA expression correlate with CRC detection and outcome. Studies also have examined the use of circulating serum mi RNA and fecal mi RNA expression as non-invasive markers for early detection. Here, we review recent evidence demonstrating the potential role of mi RNA in CRC and the implications of its use in the diagnosis, prognosis, and management of CRC.