As part of a multisite initiative to evaluate outreach targeting underserved HIV-infected individuals, we describe baseline characteristics of unstably housed HIV-infected individuals from New York City, and their health care access and utilization patterns. Interviews with 150 HIV-infected single room occupancy (SRO) hotel residents on health care access and utilization, barriers to accessing health care, demographic characteristics, history of incarceration, severity of HIV disease, depressive symptoms, substance use, and exposure to violence were conducted. Most participants were 40 years of age or older, male, black or Latino, had public insurance, a history of substance use, depressive symptoms, and a CD4(+) count above 200 cells/mm(3). Access to and utilization of care was high with 91% reporting having a regular provider, 95% identifying a non-emergency department (ED) clinic or office as their usual location of care, 89% reporting at least one ambulatory visit, and 82% reporting optimal (>/=2) ambulatory visits during the previous 6 months. Additionally, 45% reported at least one ED visit, and 30% at least one hospitalization within the previous 6 months. Among black and Latino marginalized SRO hotel residents in New York City, this study found surprisingly high measures of access to and utilization of ambulatory care services, along with high use of acute care services. Understanding HIV-related health services access and utilization patterns among marginalized populations is essential to improve their HIV care. These patterns of high levels of access to and utilization of health care services contradict clinical experiences and other studies, and require further exploration.