Objective: The evidence for central stimulant (CS) treatment in ADHD is strong in some respects but not with respect to unselected clinical material and long-term effects over the life course cycle. The objective of this study was to explore differences in vocational, psychiatric, and social impairment, including crime and substance abuse, among adults with ADHD, treated or not, with CS drugs before age 18. Method: A clinical population of men (N = 343) and women (N = 129) seeking CS treatment as adults was assessed within a specific program for such treatment. Clinical information and data collected by structured instruments were available. Results: Previously CS-treated persons had a lower frequency of problems (alcohol/substance abuse, criminality), and of certain psychiatric disorders (depressive, anxiety and personality ones). Most differences were substantial. Conclusion: The study supports the assumption that CS treatment during childhood/adolescence offers some protection against the development of a range of problems known to characterize adult ADHD patients.