This study examines ethnic variations in health insurance coverages and patterns of hospital emergency room use among 19,565 patient-visits to a private community hospital ER occurring in the calendar year of 1999. Using logistic regression analyses, the likelihood of hospital emergency room use are estimated for selected health diagnoses for four race/ethnic groups: African American, Hispanic, Non-Hispanic white, and ?other ethnicity.? The effects of health insurance coverages on patterns of ethnic ER use are estimated to assess how type of insurance coverage predicts patterns of use for specific accident/disease categories and how insurance coverage may potentially mediate patterns of use for specific sociodemographic groups. Patient condition categories for ER use are measured based upon whether the diagnostic code (ICD-9-CM) represents a clear emergency (accidents and injuries), an urgent need for care (infections or illnesses), or a potentially preventable emergency (respiratory, genitourinary, mental health, digestive illnesses). Results indicate that ethnic minorities are significantly less likely to be covered by private health insurance and are more likely to be uninsured than whites. Blacks are 1.5 times more likely, and Hispanics are 2.3 times more likely than whites to be uninsured (p<.01). Blacks were .67 times less likely and Hispanics .411 times less likely than whites to have private health insurance (p<.01). Insurance coverage facilitated hospital ER use for specific illnesses. However, type of insurance arrangement affected hospital ER use for specific need categories differently. Controlling for insurance arrangements ethnic minorities are more likely to use the ER for potentially preventable emergencies related to respiratory, genitourinary and digestive problems, whereas whites are more likely to use the ER for accidents and injuries and mental illness. Implications for theory and research are discussed. [ABSTRACT FROM AUTHOR]