Consumption of olive oil has been related to reduced risk of several diseases, including various neoplasms. In this paper, we reviewed epidemiological studies on olive oil and cancer published up to 2010. We performed a systematic literature search in the Medline database and, after assessment of relevant papers, we included 25 studies providing original data on olive oil consumption and cancer risk. We also performed a meta-analysis of studies of breast cancer, calculating the pooled relative risk (RR), and the corresponding 95% confidence intervals (CI), for high vs. low olive oil consumption. Several studies conducted in Southern Europe reported olive oil consumption as a favourable indicator of breast, digestive tract, and particularly upper aero-digestive tract cancers. For the latter, after adjustment for alcohol and tobacco use, the RRs between extreme levels of olive oil consumption were 0.3-0.4, and there was an over 5-fold difference in risk between subjects consuming mainly olive oil and those consuming mainly butter. The summary RR of breast cancer was 0.62 (95% CI, 0.44-0.88) for the highest vs. lowest level of olive oil consumption. Thus, preferring olive oil to other added lipids, particularly those rich in saturated fats, can decrease the risk of upper digestive and respiratory tract neoplasms, breast and, possibly, colorectal and other cancer sites.