Weight change is an important risk factor for mortality. The association of weight change with mortality is frequently shown as a reverse J-shaped curve. 1,2) Weight loss in overweight or obese people and weight gain in underweight people have beneficial effects on health. 1) However studies have reported conflicting results depending on ethnicity and age groups. While some studies reported that weight loss and weight gain increased mortality, 3,4) others found no associations. 5) Instead of using baseline body mass index (BMI) as in previous Background: Weight change is a known risk factor for mortality. Previous Korean studies only considered mortality consequences of weight change between two time points over relatively short periods. This study investigated whether body mass index (BMI) trajectory patterns were associated with all cause-mortality based on continuous BMI observations during a 10-year follow-up period among Korean older adults. Method: This study analyzed data from the 2006-2016 Korean Longitudinal Study of Aging database. The participants included in this study were 3,478 people aged 65 years or older who have measured BMI more than once. A trajectory model was developed to classify different homogeneous trajectory subgroups according to BMI, and Cox proportional hazards models were used to investigate the association of BMI trajectory with allcause mortality. Result: We identified four trajectory groups: obese (OG); overweight (OWG); high normal weight (HNWG); and low normal weight (LNWG). The LNWG and HNWG experienced continuous weight loss during the study period. Trajectories with higher BMI were associated with lower mortality. The adjusted hazard ratios (95% confidence intervals) for all-cause mortality in the LNWG, HNWG, and OWG were 2.40 (1.69-3.40), 1.75 (1.26-2.45), and 1.38 (0.99-1.96), respectively, compared with those in the OG. Conclusion: We found that the lower the BMI of the weight trajectory group, the higher the mortality over 10 years in Korean older adults. This result suggested that baseline obesity status and degree of weight loss during follow-up contributed to mortality in later life.