The objective was to quantify the prevalence of dual diagnosis and to evaluate the characteristics of these patients from community mental health and substance misuse services in Madrid. The sample consisted of 837 outpatients from Madrid, 208 from mental health services and 629 from substance misuse services. We used the Mini International Neuropsychiatric Interview (MINI) and Personality Disorder Questionnaire (PDQ4+) to evaluate disorders from axis I and II. It was considered that 517 (61.8%) patients had dual pathology (current diagnoses of axis I or II disorders and an addictive disorder): 36,1% in mental health services and 70,3% in substance misuse services. There were fewer males amongst the dual patients and it was also found that they had a worse employment situation, along with higher figures of alcohol and cannabis dependence than addicts without dual diagnoses (n=194). When comparing them with patients with mental disorder diagnoses only, excluding substance use disorder (n=126), there were differences in all socio-demographic characteristics analyzed, and dual patients were associated with diagnoses of bipolar disorder, agoraphobia, generalized anxiety disorder, post-traumatic stress disorder, and had more suicide risk and different personality disorders. Thus, dual pathology is higher in patients who are in treatment and have differential characteristics (higher suicide risk, worse employment situation) that suggest greater severity that could be of help in the planning of care resource policies for these patients.