Various guidelines are available for the diagnosis and treatment of ADHD in adults, but not for patients with ADHD and a comorbid substance use disorder (SUD). In 2010, the Addiction Medicine Working Party, a division of the VAD (Verenigingvoor Alcohol- en andere Drugproblemen/Association for Alcohol and other Drug Problems) developed a practice guideline on how, when and by whom ADHD can be diagnosed in patients with an addiction, and how these patients should be treated. Given the high prevalence of ADHD in treatment-seeking SUD patients and the availability of valid screening instruments, all SUD patients should be screened for ADHD as soon as their drug use has stabilized. Acquiring information from external sources as well as clinical observation and questionnaires are important tools for the establishment of the diagnosis of ADHD. Integrated treatment primarily includes psycho-education, coaching and cognitive behavioural therapy in addition to pharmacotherapy. Evidence-based treatments for addiction may also be effective in patients with concomitant ADHD, provided the methods are adapted to the limitations that are associated with this condition.