OBJECTIVE: Marginalized racial/ethnic populations showed higher rates of asthma prevalence and high-cost healthcare utilization for asthma. However, few studies investigated the disproportionate financial burden of asthma among the underrepresented racial/ethnic groups. This study aims to estimate the direct cost of asthma by severity and race/ethnicity and examine the moderating effects of race/ethnicity on the relationship between asthma severity and the cost. METHODS: This study employs a retrospective study design to estimate the direct cost of asthma for hospitalizations, ED visits, and outpatient visits. Nevada claims data were used from Q4 2015 to Q4 2021. Generalized linear models (GLMs) were used to estimate the direct cost of asthma and test the moderating effects of race/ethnicity. RESULTS: The direct cost increased as asthma severity intensified across the three settings. The direct cost rose from 2148 (Hospitalizations), 291 (ED visits), and 177 (Outpatient visits) among those with mild asthma to 0464, 0857, and 116 among those with severe asthma. The direct cost increased if patients were older, African Americans, or diagnosed with severe asthma. The incremental cost was greater among African American and Asian patients for ED visits, indicating the moderating effect of race/ethnicity. CONCLUSIONS: We found an incremental cost for severe asthma and the moderating effect of race/ethnicity on the relationship between asthma severity and the cost of ED and outpatient visits. The higher incremental costs among marginalized racial/ethnic groups imply that the financial burden of asthma increases on a larger scale among those racial/ethnic groups than among White patients.