Purpose: To investigate associations of perceived stress level, serum cortisol level, and telomere length of community-dwelling adults in Korea. Methods: Data of a total of 135 community-dwelling adults aged over 40 years living in D metropolitan city from December 2020 to March 2021 were collected. Perceived stress level over the past month were measured using the Perceived Stress Score. Serum cortisol level was analyzed using a chemiluminescent microparticle immunoassay. Telomere length was determined using quantitative real-time polymerase chain reaction. The statistical package SPSS 23.0 was used to perform Chi-square test, independent t-test, and Pearson’s correlation coefficient analysis. Results: There was no association between perceived stress and serum cortisol level (r=.07, p=.402). Serum cortisol level was not significantly associated with telomere length either (r=-.15, p=.081). However, the higher the perceived stress level, the shorter the telomere length (r=-.29, p=.001). Conclusion: These results suggest that perceived stress might induce physiological stress, which might partially affect gene biology. Further longitudinal research is needed to investigate the effect of perceived stress on telomere length. Intervention for relieving stress should be included in stabilizing the genetic environment of adults.