Hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, also called statins, are commonly prescribed medications that lower serum cholesterol and decrease cardiac morbidity and mortality. They also possess beneficial effects beyond their cholesterol-lowering properties. Preclinical data suggest statins exhibit pleiotropic antineoplastic effects in a variety of tumours, but clinical studies have provided conflicting data as to whether statins influence the risk of cancer. The biological underpinning of potential effects of statins in colorectal cancer and their role in its prevention or as adjuvant therapy are reviewed. Following a meta-analysis of both randomised clinical trials and epidemiological studies, it is concluded that available clinical data only support a modest, although statistically significant, protective effect of statins in colorectal cancer. Statins may impact on outcomes by decreasing the invasiveness or metastatic properties of colorectal cancer. The data supporting these hypotheses, however, are few and further studies are required to better assess these hypotheses. Statins may also exert a beneficial effect on colorectal cancer by sensitising the tumour to chemotherapeutic agents. Further research is needed to better define the role of statins in overcoming chemoresistance. The combination of statins with other drugs, such as low-dose aspirin or safer non-steroidal anti-inflammatory medications, may be useful in both the prevention and treatment of colorectal cancer.