Dual diagnosis is the co-occurrence of substance use disorder and other psychiatric disorder. Till date the existence of integrated dual diagnosis clinic (DDC) in India is not known. The Drug De-addiction and treatment centre of our hospital has initiated one of the first such clinics in India in October, 2009. In a retrospective chart-based review of consecutive patients over 28 months from August 2011 till December 2013, 287 case files of clinically confirmed dual diagnosis cases (representing 15% of all substance use disorder cases registered in our drug treatment centre) were analyzed. Mood disorders were the commonest psychiatric diagnosis (141, 49.1%), followed by psychotic disorders (65, 22.6%), anxiety and stress related disorders (58, 20.2%), organic disorders (6, 2%) and other mental disorders (22, 7.7%). Alcohol, opioid and cannabis were the common substances used. These preliminary data provide an overview of the profile of patients with dual diagnosis in a substance use treatment centre in north India. This should help in planning and delivering adequate and optimal services for this group of patients.