Abstract Background: DNA methylation clocks have been developed recently to estimate epigenetic age which is associated with chronological age in mouse and human. Changes in epigenetic age were reported in patients with health conditions including cancer. Different from genetic variations, epigenetic properties can be modified by environmental factors. Epigenetic age tests using blood samples have been offered directly to customers recently. We sought to analyze relationships between epigenetic aging and lifestyle factors, medication and aging interventions in the hope of assisting healthier living. Methods: Epigenetic age, called DNAge, is estimated using linear regression of DNA methylation levels at 206 loci containing 1344 CpGs and chronological age. Delta age is defined as the difference of epigenetic age minus chronological age. Correlations between lifestyle factors or medication and delta age of hundreds of whole blood samples were evaluated using biweight midcorrelation. Statistical significance is set at 0.05. Results: Our results showed positive correlations between accelerated epigenetic aging and BMI (bicor=0.148, p=0.009, n=311), current smoker (bicor=0.143, p=0.011, n=315), or stress (bicor=0.088, p=0.128, n=302). Factors with positive correlation but not reaching statistical significance included total cholesterol, alcohol consumption and Keto diet. Factors with negative correlation but not statistically significant included exercise, balanced diet, mostly meat, mostly vegetables, and education. Conclusions: The epigenetic age analysis of real customer data confirmed beneficial and adversarial health effects of certain lifestyle factors. The DNAge test offered proves to be useful as a biomarker for biological age and as a practical tool for monitoring and evaluation of health status which may be used in cancer epidemiology study and help cancer prevention. Citation Format: Wei Guo, Yap Ching Chew, Xiaojing Yang, Michiko Suwoto, Taikun Yamada, Xi Yu Jia. Correlation of lifestyle factors with epigenetic aging unveiled in the practice of a DNA methylation-based age test [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2332.