Oil is a common substance used for cooking and may pose development of disease like cancer if not properly regulated its usage. One indication for cancer development from oil is its peroxide value (POV), the concentration of peroxide and hydroperoxides, which result into a rancidity of fats and oil. This can damage the DNA attributed to the disease development like cancer. Mutagenicity is also a sign of cancer development. Thus, this study focuses on fresh and used canola and coconut oils and tested according to the frequency of usage during cooking such as 2, 3 and 4 times. POV was measured through titration and mutagenic property employing Ames test (direct assay only) using Salmonella typhimurium TA98. Results revealed an increasing POV on both kinds of oil when continually used for cooking. ANOVA (p>0.05) indicated a significant difference between fresh canola oil from WHO standards, which is within the standard limits but fresh coconut oil is in the borderline of 10 meg/kg thus, susceptible to oxidation. Similar findings revealed from the used cooking oil samples. Mutagenic property indicated no revertant colony from fresh samples. However, used canola samples gave high number of colony ranging from 13 ± 15.5361 to 363 ± 149.1224 while used coconut oil had 13 ± 11.2760 to 376 ± 174.5750 and positive control exhibited 368 ± 24.0901. Post Hoc multiple comparison tests gave no significant difference on the revertant colony between used cooking oil (4 repetitions) and positive control. Thus, repetitive used of cooking oil may become potent to develop mutagenic property that may lead to cancer development.