Anecdotal reports suggest school nurses and staff treat increasing numbers of public school students with chronic diseases. However, professionals know little about actual disease burden in schools. This study measured prevalence of chronic disease medication administration rates in a large, urban midwestern school district. Data from daily medication logs were recorded by school nurses during a single week. Medications and administrations were sorted by disease type. Prevalence rates were calculated for six chronic diseases: asthma, diabetes, seizures, attention deficit/hyperactivity disorder, other mental/behavioral disorders, and other diseases/conditions. Separate rates stratified by school grade, poverty level and type of school were calculated. Overall 3.12% of students received medication for chronic diseases, including 2.13% for psychiatric/mental disorders and 1.91% for attention deficit/hyperactivity disorder alone. These rates were lower than estimates from other states. Factors that contributed to this finding are reviewed.