Background and Objectives: Sexually transmitted diseases (STDs) have soared in China. To address the impact, we studied market stall vendors in eastern China. Goal: The goal was to determine STD prevalence and predictors. Study Design: A total of 1536 randomly selected market stall vendors were interviewed and tested for STDs. Results: The prevalence of any STD was 20.1% among those reporting sexual intercourse and 5.5% among those reporting never having sexual intercourse. Among those reporting sexual intercourse, chlamydia was most common (9.4%), followed by herpes (9.3%). A total of 4.5% of those reporting never having sexual intercourse had herpes infection, but none had chlamydia. Prevalence of all STDs was higher among females, and those with low education and multiple partners. The pharmacy was the major source of health care (48.8%). Conclusion: Generalizing from the results, targeting only STD clinic patients and persons reporting multiple partners for intervention will exclude a high proportion of those with STDs. More effective, less stigmatized sources of STD treatment should be developed.