Eighty seven adult prisoners (58 males, 29 females) completed the Beck Depression Inventory (BDI-II), Beck Anxiety Inventory (BAI), and a questionnaire on current health in order to examine both the prevalence of co-morbid conditions and the relation of depression and anxiety to ill-health and prior substance use. High prevalence rates of co-morbid conditions were detected among prisoners, with substance use history identified as the primary contributor to co-morbidity. In addition, better perceived mental health was associated with lower depression among prisoners, and a higher number of mental health conditions was associated with greater anxiety. Implications of co-morbid conditions of ill-health for the support of prisoners are discussed. (Contains 4 tables and 1 figure.)