OBJECTIVES: The goal of this study was to examine patient age and gender as well as racial and geographic variations in asthma prevalence among U.S. Medicaid patients.  METHODS: Patients diagnosed with asthma (International Classification of Disease, 9^th Revision, Clinical Modification [ICD-9-CM] diagnosis code 493.xx) were included in a retrospective study (January 1, 2008 to December 31, 2009) from a Medicaid fee-for-service (FFS) population. All patients were required to have a 2-year continuous Medicaid FFS enrollment in 2008 and 2009. Patients with managed care enrollment in any month during the study period were excluded. Disease prevalence was stratified by region, state, age, gender and race for all the patients. Descriptive statistics were calculated as the number and percentage of patients in each category to measure the prevalence in the sample.  RESULTS: A total of 399,572 patients were diagnosed with asthma in 2008 and 2009. For asthma patients, prevalence was the highest for those under age 40 (10.59%), followed by age groups 40 to 59 (10.45%), and 60+ (5.67%). Prevalence by race was also examined: Native American (10.38%), Black (9.73%), White (7.82%), Hispanic (7.78%) and Asian (6.06%). Higher asthma prevalence rates were observed for female (8.69%) compared to male patients (7.28%). Geographic variation was analyzed with the highest asthma prevalence observed in Missouri (14.04%), followed by New Hampshire (13.84%), Connecticut (13.12%), Ohio (12.96%) and Minnesota (12.52%). Prevalence rates were found to be highest in the Midwest (10.43%) compared to the Northeast (8.65%), West (6.96%) and Southern (6.39%) U.S. regions.  CONCLUSIONS: The current study shows that patients under age 60 have a higher probability of being diagnosed with asthma. Moreover, Native American and Black patients were more likely to be diagnosed with asthma compared to other races. Geographically, patients residing in the Midwest U.S. region have a higher risk for an asthma diagnosis.