Open access. This was a prospective, longitudinal study of patients followed for 19 years after entering specialized treatment for substance use disorders. At baseline 291 patients (mean age 38.3 years, standard deviation 11.4 years, 72% male) with high psychiatric co-morbidity were recruited; 130 (45%) had lifetime alcohol use disorder alone, while 161 (55%) had poly-substance use disorders. Time and causes of death were gathered from the Norwegian Cause of Death Registry. Lifetime psychiatric symptom disorders and substance use disorders at baseline were measured with The Composite International Diagnostic Interview and personality disorders at baseline were measured with The Millon Clinical Multiaxial Inventory II.