To determine the proportions of countywide expenditures and service delivery for the Cook County Health and Hospitals System (CCHHS), we obtained data from the CCHHS budget; CCHHS registration, program, and pharmacy databases; public health departments and organization reports; and federal agency estimates. The annual CCHHS budget of $1.2B represents 3.4% of total Cook County health care expenditures. Eight of the nine population-based proportions of health care services delivered by the CCHHS exceeded this proportion of health expenditures by factors of 1.3–8 times. These services include diagnosis of tuberculosis, sexually transmitted diseases, and cancers; care of very low birth weight babies; primary care for HIV and diabetes; and emergency room and ambulatory visits. This county health care system is a productive contributor to overall health service delivery in Cook County, and its contributions exceed its proportionate funding in eight of nine priority health areas.