To determine the seroprevalence of hepatitis C virus (HCV), hepatitis B virus (HBV) and syphilis in HIV-1-infected patients and related risk factors in Shandong province, China, we tested all eligible participants between 2000 and 2010 for the presence of anti-HCV antibody, hepatitis B surface antigen (HBsAg) and non-treponemal antibodies for syphilis after informed consent. Among 2087 HIV-infected patients, anti-HCV antibody was present in 41.2%, HBsAg in 12.6% and rapid plasma reagin (RPR) reactivity in 19.6%. In the multivariate logistic regression model, male gender (adjusted odds ratio [aOR] = 1.41), minority ethnicity (aOR = 1.72), syphilis infection (aOR = 1.40), former paid blood donors (aOR = 3.36), blood transfusion recipients (aOR = 2.91) and injection drug users (aOR = 1.98) were significantly associated with HCV infection. HCV infection (aOR = 1.40) and being men who have sex with men (aOR = 2.38) were significantly associated with syphilis infection. Co-infection with HCV, HBV and syphilis was observed frequently in all described subgroups of HIV infection. The results of this study suggest that it is necessary to screen for these viruses and syphilis in all Chinese HIV-infected patients.