Objective: To explore how ADHD may have affected the lives of older adults who meet the diagnostic criteria of ADHD, but are unaware of their diagnosis. Our second aim was to examine whether the reported symptoms change over the life span. Method: A qualitative study was conducted. Seventeen Dutch older people (>65 years) diagnosed in this study with ADHD participated in in-depth interviews. Data were analyzed according to techniques of thematic approach. Results: Seven themes emerged from the analyses. Four themes correspond to ADHD symptoms: “being active,” “being impulsive,” “attention problems,” and “mental restlessness.” In addition, the themes “low self-esteem,” “overstepping boundaries,” and “feeling misunderstood” emerged. The impact of ADHD symptoms seems to have declined with age. Conclusion: ADHD has a negative impact on late life, and older adults with the disorder may benefit from treatment. Moreover, this study’s findings call for early detection and treatment of ADHD in children and adults.