There is evidence that earlier initiation of HIV antiretroviral therapy (ART) is associated with better outcomes, including lower morbidity and mortality. Based on recent studies indicating that Medicaid enrollees are more likely to have suboptimal access to medical care, we hypothesized that HIV severity at time of ART initiation is worse for Medicaid patients than patients with other health care coverage. We conducted a US retrospective analysis of GE Centricity Outpatient Electronic Medical Records spanning 1 January 1997 through 30 September 2009. Subjects included all adult HIV patients initiating first-line ART who had CD4+ results within 90 days pre-initiation. HIV stage was defined using CD4 ranges: >500 (n=520), 351-500 (n=379), 201-350 (n=580), or ≤200 (n=406) cells/mm(3), with lower CD4 count being indicative of increased disease severity. Payer type was defined as the patient's primary payer: Medicaid, Medicare, commercial insurance, self-pay or other/unknown. After controlling for demographic and clinical covariates, cumulative logit models assessed the effect of payer type on HIV stage at ART initiation. The study included 1885 subjects with the primary payer being Medicaid (n=218), Medicare (n=330), commercial insurance (n=538), self-pay (n=159) or other/unknown (n=640). Final logit models demonstrated that, compared to patients on Medicaid, the odds of initiating ART at a higher CD4 range were significantly greater for those commercially insured (odds ratio [OR]=1.53; P=0.005), self-paying (OR=1.56; P=0.023) and other/unknown (OR=1.79; P<0.001) and similar for patients enrolled in Medicare (OR=1.11; P=0.521). Medicaid patients initiated ART at a more advanced stage of HIV than patients who were commercially insured, self-paying, or had other/unknown coverage. With HIV treatment guidelines now supporting ART initiation in patients with higher CD4 counts, these findings underscore the need for mitigating barriers, particularly in the Medicaid population, that may delay treatment initiation.