Objective Short-term mortality rates remain high among critically ill human immunodeficiency virus-1 (HIV-1) patients though long-term mortality rates have dropped. Baseline risk factors for short-term mortality have not yet been determined in China. In this paper, we herein describe clinical characteristics, laboratory findings, causes of clinical deterioration, and risk factors associated with mortality among HIV-1 patients within six months after hospital admission. Methods We carried out a prospective study of hospitalized patients in advanced stages of HIV infection. These patients started antiretroviral therapy three or four weeks after admission. Follow-up was conducted for a period of six months. We used a multivariate logistic-regression analysis to identify risk factors associated with mortality. Results A total of 141 patients met our inclusion criteria. The mean age was 41 years. Fever and weight loss were the most common clinical manifestations of advanced HIV disease. Oral candidiasis, tuberculosis, cytomegaloviremia, and pneumocystis pneumonia were the most common opportunistic infections. Significantly decreased CD4+ T-cell counts, hypoalbuminemia, anemia, hyponatremia, as well as elevated C-reactive protein (CRP) and glutamic alanine transaminase levels were common laboratory test abnormalities. The mortality rate was 21.3%. The patients who died were more likely than the survivors to have low CD4+ Tcell counts as well as low creatinine, hemoglobin, albumin, and serum sodium levels while also having longer intervals of fever and higher CRP levels. A multivariate analysis demonstrated that the independent risk factors for mortality were active tuberculosis [odds ratio (OR): 2.681; 95% confidence interval (CI), p=0.049], hyponatremia (OR: 3.027; 95% CI, p=0.015), and being at clinical stage 4 (as defined by the World Health Organization) (OR: 9.492; 95% CI, 1.200-75.065; p=0.033) within the first six months of admission. Conclusion Special consideration should be given to patients who have active tuberculosis, are at clinical stage 4, and present with hyponatremia upon admission as these were found to be important factors associated with mortality within six months of hospital admission in HIV-1 patients.