Deep-frying is now a popular cooking method all over the world due to its low cost and time-saving property. It also provides special and likeable flavor, helps prolong shelf lives of commercial products, and offering food products of stable quality. However, by- products formed during the frying process, such as malonaldehyde, were shown to be harmful to human health. Such compounds can be taken in when having fried foods, potentially inducing or promoting some diseases. However, there is limited research studying the direct effects of frying oil consumption on cancer. In order to have a better understanding of the effects on cancer by frying oil, we used a well-established AOM/DSS- induced colon cancer animal model to study the impact by frying oil. After 10-week treatment with diet containing deep-frying oil (3.8% in diet) or with un-oxidized oil (10% in diet), the mice showed enhanced tumorigenesis in colon, where the total tumor burden significantly increased (4.5 ± 1.9 mm2 for the treatment group, compared with 0.5 ± 0.5 mm2 for the control group, P < 0.05). Also, the expression of pro-inflammatory and pro- tumorigenic cytokines (Mcp-1, Inf-γ, Il-6, Il-1β, Myc, Axin2 and Vegf) were increased in the mice treated with frying oil diets. Together the results showed that consumption of deep-frying oil promoted the colorectal cancer in mice, providing more detailed information for health instruction.