Two patients with a multi-substance use disorder and an apparent comorbid adhd disorder were given psychiatric treatment for both illnesses. Each patient had a comorbid affective disorder. In both cases the approach was based on the Belgian guideline ‘Good clinical practice in the recognition and treatment of young adults with addiction problems’. We use the case-reports to demonstrate the usefulness and relevance of the guideline in an outpatient setting compared to an inpatient setting and look particularly at the implications of other kinds of comorbidity encompassed by the guideline.