Industrial workers are a vulnerable population for HIV and sexually transmitted infections (STIs). This cross-sectional study assessed the general knowledge about sexually transmitted infections (STIs) and HIV transmission risk among 289 industrial workers in Northern Vietnam. Results indicated that most workers could identify common routes of HIV transmissions and were aware of common STIs. However, insufficient knowledge about HIV transmission via anal sex practices, as well as common signs and symptoms of STIs were observed. Gender, marital status, education, locality status and health information sources were associated with the knowledge. This study reveals a gap of knowledge about HIV and other STIs, and suggested further tailored education interventions to improve the knowledge and promote sexual health-seeking behaviors in industrial workers.