This paper explores disparities in health care access for undocumented immigrants in the United States. Using the case of California, we find that less than half of undocumented immigrants in this state report having health insurance. Additionally, our estimates show that, among the insured, US-born and naturalized citizens are significantly more likely to have a doctor visit in the previous year when compared to undocumented immigrants (aOR = 1.53%; 95% CI 1.15 - 2.04, aOR = 1.40%; 95% CI 1.05 - 1.87, respectively). Further, we find that US-born citizens are significantly more likely to use the ER in the previous year than undocumented immigrants, independent of insurance status. Our findings suggest that undocumented immigrants not only face barriers to obtain health insurance, but even with health insurance they face barriers to access health care services.