The aims of this study were to describe causes of death during the 10-year period between 1995 and 2004 in a large urban jail in Chicago; to compare disease specific mortality rates between the jail population and the general population; to explore demographic and incarceration characteristics of the inmates who died in the jail by cause of death; and to examine gender difference in demographic characteristics, incarceration patterns, and causes of death. A total of 178 deaths occurring in the jail over a 10-year period (1995–2004) were reviewed. Age-adjusted disease-specific mortality rates were computed for the jail population and compared with the rates in the US general population. Cause of death, demographic variables, and incarceration related factors were retrieved from multiple computerized databases. Descriptive analyses were performed to examine demographic and incarceration-related patterns by cause of death and gender. Heart disease was the most frequent cause of death in the jail population, followed by cerebrovascular disease and suicide. Mortality rates for heart diseases, infectious/inflammatory conditions and suicide were higher for jail inmates than the general population. Black inmates accounted for the majority of deaths due to illnesses and homicide, and a much higher proportion of white and Hispanic inmates were involved in suicide deaths. Deaths due to drug overdose or withdrawal were disproportionately higher among female inmates compared with male inmates. Consistent review of mortality rates and causes of deaths in jail can be a useful tool to better understand health issues and needs of jail inmates. Surveillance of acute and chronic illnesses and strategic reengineering of jail health care is a key to quality improvement for incarcerated populations for whom the jail system becomes their primary care provider.