This study provides data on substance use patterns, including medications, among female inmates in Canadian federal prisons. The participants were interviewed regarding their substance use and their psychological condition before and during incarceration. Their medication cards were also analyzed. The results show that a large proportion (66.9 %) of these incarcerated women reported substance abuse prior to incarceration and exhibited psychological disorders. In prison, if the illicit substance use remained low, most subjects had prescriptions for more than one medication. Furthermore, women with psychotropic medication prescriptions in their file had, on average, prescriptions for two different psychotropic medications. Significant relationships were found between substance misuse before incarceration and illicit substance use or and psychotropic medication use during incarceration. These results support the need to develop integrated services for both addiction and mental health for female offenders during incarceration.