Delayed diagnosis of HIV infection is associated with advanced immunosuppression and increased risk of onward transmission. Little data exists regarding factors associated with diagnostic delays among patients presenting with advanced HIV disease in China. Medical records of patients with HIV/AIDS hospitalized at a 2000-bed tertiary hospital in Beijing, China between 1997 and 2012 were retrospectively reviewed. Demographic and clinical data of patients newly diagnosed with HIV at the hospital were abstracted. Patient characteristics, disease parameters, and the time interval between the first medical visit and the visit leading to HIV diagnosis were compared among three periods: 1997-2002, 2003-2008 and 2009-2012. Chi-square, Kruskal-Wallis and logistic regression analyses were used as appropriate. A quarter of patients (72/279) were newly diagnosed with HIV at the hospital, consisting of 11, 29 and 32 patients in 1997-2002, 2003-2008 and 2009-2012 respectively. The median time delay between the first medical visit and the visit leading to HIV diagnosis decreased over time from 91 days among patients diagnosed before 2002, to 75 days between 2003 to 2008, and 39 days after 2009 (p = 0.036). However, the median CD4+T cell count at diagnosis was 26 cells/μL [interquartile range 3-132 cells/μL] in 1997-2002, and remained unchanged across time intervals. Forty-one (57%) patients had AIDS-defining conditions and Pneumocystis jiroveci pneumonia was the most common opportunistic infection (31 cases). These results reveal persistent missed opportunities for timely HIV testing among patients with advanced disease. Strategies for promoting early HIV testing in healthcare settings are needed in China.