OBJECTIVES: This study examined health insurance coverage among immigrants who are not US citizens and among individuals from the 16 countries with the largest number of immigrants living in the United States. METHODS: We analyzed data from the 1998 Current Population Survey, using logistic regression to standardize rates of employer-sponsored coverage by country of origin. RESULTS: In 1997, 16.7 million immigrants were not US citizens. Among non-citizens, 43% of children and 12% of elders lacked health insurance, compared with 14% of non-immigrant children and 1% of non-immigrant elders. Approximately 50% of non-citizen full-time workers had employer-sponsored coverage, compared with 81% of non-immigrant full-time workers. Immigrants from Guatemala, Mexico, El Salvador, Haiti, Korea, and Vietnam were the most likely to be uninsured. Among immigrants who worked full-time, sociodemographic and employment characteristics accounted for most of the variation in employer health insurance. For Central American immigrants, legal status may play a role in high un-insurance rates. CONCLUSIONS: Immigrants who are not US citizens are much less likely to receive employer-sponsored health insurance or government coverage; 44% are uninsured. Ongoing debates on health insurance reform and efforts to improve coverage will need to focus attention on this group.