Abstract: Objective To investigate the characteristics and associated factors of commercial sexual contacts among attendees at the sexually transmitted disease (STD) clinics in Guangdong Province. Methods We recruited attendees at the STD clinics in Dongguan and Zhongshan cities, and collected the information on demographic characteristics, history of commercial sex behavior, and STDs testing. The Logistic regression model was applied to analyze possible associated factors. Results In total, 259 (13.1%) attendees reported a history of commercial sex in the past six months. The prevalence of commercial sex in men was higher than that among women (χ²=129.173,P<0.001). The proportions of condom use at last sex intercourse, the rates of testing for human immunodeficiency virus (HIV) and syphilis separately and simultaneously, and the rate of HIV tested positive for people who pay for sex were all higher than those among people without commercial sex (all P<0.05). Gender, monthly income, habitation status, and STD history were associated with commercial sex behavior. Conclusions The prevalence of commercial sex behavior among attendees at the STD clinics in Guangdong Province was high. Males, especially those with lower income, or without a STD history, or live alone, may tend to have commercial sexual contacts.