Background: Little is known about the prevalence of attention-deficit hyperactivity disorder (ADHD) among older adults. Aims: To estimate the prevalence of the syndromatic and symptomatic DSM-IV ADHD diagnosis in older adults in The Netherlands. Method: Data were used from the Longitudinal Aging Study Amsterdam (LASA). At baseline, 1494 participants were screened with an ADHD questionnaire and in 231 respondents a structured diagnostic interview was administered. The weighted prevalence of ADHD was calculated. Results: The estimated prevalence rate of syndromatic ADHD in older adults was 2.8%; for symptomatic ADHD the rate was 4.2%. Younger elderly adults (60-70 years) reported significantly more ADHD symptoms than older elderly adults (71-94 years). Conclusions: This is the first epidemiological study on ADHD in older persons. With a prevalence of 2.8% the study demonstrates that ADHD does not fade or disappear in adulthood and that it is a topic very much worthy of further study. Declaration of interest A.T.F.B. has received an unrestricted research grant from Eli Lilly and AstraZeneca and has been a speaker for Lundbeck and Eli Lilly. J.J.S.K. is a speaker for Eli Lilly, Janssen and Shire and has received unrestricted research grants for this study from Shire, as well as for another study from Janssen.