Background: HIV testing is critical for both HIV treatment and prevention. Expanding testing in hospital settings can identify undiagnosed HIV infections. Methods: To evaluate the feasibility of universally offering HIV testing during emergency department (ED) visits and inpatient admissions, 9 hospitals in the Bronx, New York and 7 in Washington DC undertook various efforts to encourage staff to offer HIV testing routinely. Outcomes included the percentage of encounters with an HIV test, the change from year 1 to year 3, and the percentages of tests that were HIV-positive and new diagnoses. Results: From February 1, 2011 to January 31, 2014, HIV tests were conducted during 6.5% of 1,621,016 ED visits and 13.0% of 361,745 inpatient admissions in Bronx hospitals and 13.8% of 729,172 ED visits and 22.0% of 150,655 inpatient admissions in DC, with wide variation by hospital. From year 1 to year 3, testing was stable in the Bronx (6.6% to 6.9% of ED visits, 13.0% to 13.6% of inpatient admissions), but increased in DC (11.9% to 15.8% of ED visits, 19.0% to 23.9% of inpatient admissions). Overall, in the Bronx 0.4% (408) of ED HIV tests were positive, 0.3% (277) were new diagnoses; 1.8% (828) of inpatient tests were positive, 0.5% (244) were new diagnoses. In DC, 0.6% (618) of ED tests were positive, 0.4% (404) were new diagnoses; 4.9% (1349) of inpatient HIV tests were positive, 0.7% (189) were new diagnoses. Conclusion: Hospitals consistently identified previously undiagnosed HIV infections, but universal offer of HIV testing proved elusive.