A cross-sectional survey was conducted to determine the sociodemographic correlates of herpes simplex virus type 2 (HSV-2) infection among male and female commercial sex workers in Kunming, Yunnan Province of China. HSV-2 prevalence was 33.0%, human immunodeficiency virus (HIV) infection was 2.4% and hepatitis C virus (HCV) infection was 6.8%. Subjects who were positive for HSV-2 had a significantly higher prevalence of HIV infection (5.5% versus 0.9%, P = 0.002; odds ratio [OR]: 6.4, P = 0.006) and HCV infection (18.7% versus 2.4%, P < 0.001; OR: 7.6, P < 0.001) compared with HSV-2-negative individuals. Risk factors that increased the odds of HSV-2 infection were HIV infection, HCV infection, being female, and having a steady sex partner within the last six months (P < or = 0.01). In a multivariate analysis, being female (OR: 6.6, P < 0.001), having HCV infection (OR: 5.9, P < 0.001) and having a sex partner within the last six months (OR: 2.2, P < 0.05) showed greater odds of being infected with HSV-2. A strong relationship was found between HSV-2, HIV and HCV infections.