Faecal pH and cholate are two important factors that can affect colon tumorigenesis, and can be modifiedby diet. In this study, the effects of two Chinese traditional cooking oils (pork oil and canola/rapeseed oil) on thepH and the cholic acid content in feces, in addition to colon tumorigenesis, were studied in mice. Kunming micewere randomized into various groups; negative control group (NCG), azoxymethane control group (ACG), porkoil group (POG), and canola oil Ggroup (COG) . Mice in the ACG were fed a basic rodent chow; mice in POGand COG were given 10% cooking oil rodent chow with the respective oil type. All mice were given four weeklyAOM (azoxymethane) i.p. injections (10mg/kg). The pH and cholic acid of the feces were examined every twoweeks. Colon tumors, aberrant crypt foci and organ weights were examined 32 weeks following the final AOMinjection. The results showed that canola oil significantly decreased faecal pH in female mice (P<0.05), but hadno influence on feces pH in male mice (P>0.05). Pork oil significantly increased the feces pH in both male andfemale mice (P<0.05). No significant change was found in feces cholic acid content when mice were fed 10%pork oil or canola oil compared with the ACG. Although Kunming mice were not susceptible to AOM-inducedtumorigenesis in terms of colon tumor incidence, pork oil significantly increased the ACF number in male mice.Canola oil showed no influence on ACF in either male or female mice. Our results indicate that cooking oil effectsfaecal pH, but does not affect the faecal cholic acid content and thus AOM-induced colon neoplastic ACF ismodified by dietary fat.