Opt-out HIV screening is recommended by the CDC for patients in all healthcare settings. We examined correlates of HIV testing refusal among urban emergency department (ED) patients. Confidential free HIV screening was offered to 32,633 ED patients in an urban tertiary care facility in Washington, DC, during May 2007–December 2011. Demographic differences in testing refusals were examined using χ2 tests and generalized linear models. HIV testing refusal rates were 47.7 % 95 % CI (46.7–48.7), 11.7 % (11.0–12.4), 10.7 % (10.0–11.4), 16.9 % (15.9–17.9) and 26.9 % (25.6–28.2) in 2007, 2008, 2009, 2010 and 2011 respectively. Persons 33–54 years of age [adjusted prevalence ratio (APR) 1.42, (1.36–1.48)] and those ≥55 years [APR 1.39 (1.31–1.47)], versus 33–54 years; and females versus males [APR 1.07 (1.02–1.11)] were more likely to refuse testing. Opt-out HIV testing is feasible and sustainable in urban ED settings. Efforts are needed to encourage testing among older patients and women.