ABSTRACT. Objectives: To increase insight into the effect of attention-deficit/hyperactivity disorder (ADHD) on health in general in older adults. Design: Two-phase sampling side-study. Setting: Longitudinal Aging Study Amsterdam (LASA). Participants: Two hundred twenty-three randomly selected LASA respondents. Measurements: Information was collected during home visits on physical health, medication use, and lifestyle characteristics in Phase 1 and on ADHD diagnosis in Phase 2. The associations between independent variables and ADHD were examined with linear and logistic regression analyses. Results: The adjusted regression estimates of the linear regression analysis showed that the number of ADHD symptoms was positively associated with the presence of chronic nonspecific lung diseases (CNSLD) (B = 2.58, P = .02), cardiovascular diseases (B = 2.18, P = .02), and number of chronic diseases (B = 0.69, P = .04) and negatively associated with self-perceived health (B = -2.83, P = .002). Lifestyle is not a mediator of the association between ADHD and physical health. Conclusion: Attention-deficit/hyperactivity disorder in older adults was associated with chronic physical illness and poorer self-perceived health. Contrary to expectations, there were no associations between symptoms of ADHD and lifestyle variables.