We surveyed 276 club drug users in Shanghai, China. Overall, 43.8% reported ≥2 sex partners in the past 30 days, and 48.9% reported having sex with non-regular partners, 67.4% of whom had unprotected sex. Having ≥2 recent sex partners was associated with being 35 years or older, male, living with friends or others, introduced to club drug use by non-regular sex partners, using methamphetamine recently, self-identified as gay/lesbian or bisexual, had sexual debut before 20 years old, and recently had sex under the influence of drugs. Having unprotected sex with non-regular partners in the past 30 days was associated with lower education levels, having sex to obtain drugs, and lower levels of HIV/AIDS knowledge. Club drug users should be targeted for intervention programs. Future research needs to identify other protective and risk factors for sexual risk behaviors and design interventions to reduce club drug use and associated sexual risk behaviors.