There is evidence that persons with severe mental illness have higher rates of chronic health conditions and a reduced life expectancy compared with the general population. For example, between 58% and 74% of persons with severe mental illness report at least one chronic health problem, such as hypertension, diabetes, and pulmonary disease. Further, persons with severe mental illness, particularly those diagnosed as having schizophrenia, live fewer years on average and have higher relative mortality risks than the general population. The medical needs of persons with mental illness are of particular concern because our mental health and primary health care systems are not well integrated, and there is evidence that the health care needs of persons with mental illness often go unmet. In this context, there is little information about how the general medical problems of persons with severe mental illness who have a history of incarceration—defined here as one or more incarcerations in a local jail during a five-year study period—compare with the medical problems of persons with mental illness who do not have a history of incarceration. This gap in our knowledge is of concern because incarcerated individuals, in general, have higher rates of chronic illness, such as diabetes, coronary artery disease, and infectious diseases. Compared with consumers with no history of incarceration, are persons with severe mental illness and a history of incarceration at even greater risk of general medical problems? The aim of this study was to contribute to our knowledge about the complex needs of persons with mental illness by examining the synergistic effects of severe mental illness and incarceration on the general medical problems of persons with mental illness.