To explore whether disparities exist among persons seeking emergency department (ED) care related to marijuana use, we developed marijuana case (MJCs) definitions, provided an overview of the prevalence of ED visits related to marijuana use, and identified differences in MJCs by age, gender, and geographic location. Males and persons aged 18-44 years constituted a higher proportion of MJCs, which may be related to differences in usage patterns as identified by the BehaviOral Risk Factor Surveillance System. Denver and Arapahoe Counties had a higher percentage of pediatric MJCs. More advanced spatial analysis will describe details of geographic disparities in the research.